commands: add example for 'hg add'

extensions: refuse to load extensions if minimum hg version not met As the author of several 3rd party extensions, I frequently see bug reports from users attempting to run my extension with an old version of Mercurial that I no longer support in my extension. Oftentimes, the extension will import just fine. But as soon as we run extsetup(), reposetup(), or get into the guts of a wrapped function, we encounter an exception and abort. Today, Mercurial will print a message about extensions that don't have a "testedwith" declaring explicit compatibility with the current version. The existing mechanism is a good start. But it isn't as robust as I would like. Specifically, Mercurial assumes compatibility by default. This means extension authors must perform compatibility checking in their extsetup() or we wait and see if we encounter an abort at runtime. And, compatibility checking can involve a lot of code and lots of error checking. It's a lot of effort for extension authors. Oftentimes, extension authors know which versions of Mercurial there extension works on and more importantly where it is broken. This patch introduces a magic "minimumhgversion" attribute in extensions. When found, the extension loading mechanism will compare the declared version against the current Mercurial version. If the extension explicitly states we require a newer Mercurial version, a warning is printed and the extension isn't loaded beyond importing the Python module. This causes a graceful failure while alerting the user of the compatibility issue. I would be receptive to the idea of making the failure more fatal. However, care would need to be taken to not criple every hg command. e.g. the user may use `hg config` to fix the hgrc and if we aborted trying to run that, the user would effectively be locked out of `hg`! A potential future improvement to this functionality would be to catch ImportError for the extension/module and parse the source code for "minimumhgversion = 'XXX'" and do similar checking. This way we could give more information about why the extension failed to load.

run-tests: add --slowtimeout and use it for slow tests

serve: unify cmdutil.service() calls of commandserver and hgweb

hgweb: extract factory function of httpservice object The next patch will merge the cmdutil.service() calls of both commandserver and hgweb. Before doing it, this patch wipes out the code specific to hgweb from commands.serve().

hgweb: move httpservice object from commands module This avoids the deep import of hgweb.server at the commands module.

merge: move almost all change/delete conflicts to resolve phase (BC) (API) We have finally laid all the groundwork to make this happen. The only change/delete conflicts that haven't been moved are .hgsubstate conflicts. Those are trickier to deal with and well outside the scope of this series. We add comprehensive testing not just for the initial selections but also for re-resolves and all possible dirstate transitions caused by merge tools. That testing managed to shake out several bugs in the way we were handling dirstate transitions. The other test changes are because we now treat change/delete conflicts as proper merges, and increment the 'merged' counter rather than the 'updated' counter. I believe this is the right approach here. For third-party extensions, if they're interacting with filemerge code they might have to deal with an absentfilectx rather than a regular filectx. Still to come: - add a 'leave unresolved' option to merges - change the default for non-interactive change/delete conflicts to be 'leave unresolved' - add debug output to go alongside debug outputs for binary and symlink file merges

test-merge-changedelete.t: print out debugmergestate We're going to use this to verify the merge state in upcoming patches.

debugmergestate: also recognize change/delete conflicts in the merge state We're going to use this for tests in upcoming patches.

debugmergestate: print out null nodes as 'null' This is so much easier to read than a long string of zeroes, and we're going to have a lot more of these nodes once change/delete conflicts are part of the merge state.