Test hiding some commands (which also happens to hide an entire category).

  $ hg --config help.hidden-command.clone=true \

  > --config help.hidden-command.init=true help

  Mercurial Distributed SCM

  list of commands:

  Remote repository management:

   incoming      show new changesets found in source

   outgoing      show changesets not found in the destination

   paths         show aliases for remote repositories

   pull          pull changes from the specified source

   push          push changes to the specified destination

   serve         start stand-alone webserver

  Change creation:

   commit        commit the specified files or all outstanding changes

  Change manipulation:

   backout       reverse effect of earlier changeset

   graft         copy changes from other branches onto the current branch

   merge         merge another revision into working directory

  Change organization:

   bookmarks     create a new bookmark or list existing bookmarks

   branch        set or show the current branch name

   branches      list repository named branches

   phase         set or show the current phase name

   tag           add one or more tags for the current or given revision

   tags          list repository tags

  File content management:

   annotate      show changeset information by line for each file

   cat           output the current or given revision of files

   copy          mark files as copied for the next commit

   diff          diff repository (or selected files)

   grep          search for a pattern in specified files

  Change navigation:

   bisect        subdivision search of changesets

   heads         show branch heads

   identify      identify the working directory or specified revision

   log           show revision history of entire repository or files

  Working directory management:

   add           add the specified files on the next commit

   addremove     add all new files, delete all missing files

   files         list tracked files

   forget        forget the specified files on the next commit

   purge         removes files not tracked by Mercurial

   remove        remove the specified files on the next commit

   rename        rename files; equivalent of copy + remove

   resolve       redo merges or set/view the merge status of files

   revert        restore files to their checkout state

   root          print the root (top) of the current working directory

   shelve        save and set aside changes from the working directory

   status        show changed files in the working directory

   summary       summarize working directory state

   unshelve      restore a shelved change to the working directory

   update        update working directory (or switch revisions)

  Change import/export:

   archive       create an unversioned archive of a repository revision

   bundle        create a bundle file

   export        dump the header and diffs for one or more changesets

   import        import an ordered set of patches

   unbundle      apply one or more bundle files

  Repository maintenance:

   manifest      output the current or given revision of the project manifest

   recover       roll back an interrupted transaction

   verify        verify the integrity of the repository

  Help:

   config        show combined config settings from all hgrc files

   help          show help for a given topic or a help overview

   version       output version and copyright information

  additional help topics:

  Mercurial identifiers:

   filesets      Specifying File Sets

   hgignore      Syntax for Mercurial Ignore Files

   patterns      File Name Patterns

   revisions     Specifying Revisions

   urls          URL Paths

  Mercurial output:

   color         Colorizing Outputs

   dates         Date Formats

   diffs         Diff Formats

   templating    Template Usage

  Mercurial configuration:

   config        Configuration Files

   environment   Environment Variables

   extensions    Using Additional Features

   flags         Command-line flags

   hgweb         Configuring hgweb

   merge-tools   Merge Tools

   pager         Pager Support

   rust          Rust in Mercurial

  Concepts:

   bundlespec    Bundle File Formats

   evolution     Safely rewriting history (EXPERIMENTAL)

   glossary      Glossary

   phases        Working with Phases

   subrepos      Subrepositories

  Miscellaneous:

   deprecated    Deprecated Features

   internals     Technical implementation topics

   scripting     Using Mercurial from scripts and automation

  (use 'hg help -v' to show built-in aliases and global options)

Test hiding some topics.

  $ hg --config help.hidden-topic.deprecated=true \

  > --config help.hidden-topic.internals=true \

  > --config help.hidden-topic.scripting=true help

  Mercurial Distributed SCM

  list of commands:

  Repository creation:

   clone         make a copy of an existing repository

   init          create a new repository in the given directory

  Remote repository management:

   incoming      show new changesets found in source

   outgoing      show changesets not found in the destination

   paths         show aliases for remote repositories

   pull          pull changes from the specified source

   push          push changes to the specified destination

   serve         start stand-alone webserver

  Change creation:

   commit        commit the specified files or all outstanding changes

  Change manipulation:

   backout       reverse effect of earlier changeset

   graft         copy changes from other branches onto the current branch

   merge         merge another revision into working directory

  Change organization:

   bookmarks     create a new bookmark or list existing bookmarks

   branch        set or show the current branch name

   branches      list repository named branches

   phase         set or show the current phase name

   tag           add one or more tags for the current or given revision

   tags          list repository tags

  File content management:

   annotate      show changeset information by line for each file

   cat           output the current or given revision of files

   copy          mark files as copied for the next commit

   diff          diff repository (or selected files)

   grep          search for a pattern in specified files

  Change navigation:

   bisect        subdivision search of changesets

   heads         show branch heads

   identify      identify the working directory or specified revision

   log           show revision history of entire repository or files

  Working directory management:

   add           add the specified files on the next commit

   addremove     add all new files, delete all missing files

   files         list tracked files

   forget        forget the specified files on the next commit

   purge         removes files not tracked by Mercurial

   remove        remove the specified files on the next commit

   rename        rename files; equivalent of copy + remove

   resolve       redo merges or set/view the merge status of files

   revert        restore files to their checkout state

   root          print the root (top) of the current working directory

   shelve        save and set aside changes from the working directory

   status        show changed files in the working directory

   summary       summarize working directory state

   unshelve      restore a shelved change to the working directory

   update        update working directory (or switch revisions)

  Change import/export:

   archive       create an unversioned archive of a repository revision

   bundle        create a bundle file

   export        dump the header and diffs for one or more changesets

   import        import an ordered set of patches

   unbundle      apply one or more bundle files

  Repository maintenance:

   manifest      output the current or given revision of the project manifest

   recover       roll back an interrupted transaction

   verify        verify the integrity of the repository

  Help:

   config        show combined config settings from all hgrc files

   help          show help for a given topic or a help overview

   version       output version and copyright information

  additional help topics:

  Mercurial identifiers:

   filesets      Specifying File Sets

   hgignore      Syntax for Mercurial Ignore Files

   patterns      File Name Patterns

   revisions     Specifying Revisions

   urls          URL Paths

  Mercurial output:

   color         Colorizing Outputs

   dates         Date Formats

   diffs         Diff Formats

   templating    Template Usage

  Mercurial configuration:

   config        Configuration Files

   environment   Environment Variables

   extensions    Using Additional Features

   flags         Command-line flags

   hgweb         Configuring hgweb

   merge-tools   Merge Tools

   pager         Pager Support

   rust          Rust in Mercurial

  Concepts:

   bundlespec    Bundle File Formats

   evolution     Safely rewriting history (EXPERIMENTAL)

   glossary      Glossary

   phases        Working with Phases

   subrepos      Subrepositories

  (use 'hg help -v' to show built-in aliases and global options)