worker: ability to disable thread unsafe tasks The worker on Windows is implemented using a thread pool. If worker tasks are not thread safe, badness can occur. In addition, if tasks are executing CPU bound code and holding onto the GIL, there will be non-substantial overhead in Python context switching between active threads. This can result in significant slowdowns of tasks. This commit teaches the code for determining whether to use a worker to take thread safety into account. Effectively, thread unsafe tasks don't use the thread-based worker on Windows. Differential Revision: https://phab.mercurial-scm.org/D3962

worker: rename variable to reflect constant Differential Revision: https://phab.mercurial-scm.org/D3961

worker: use one pipe per posix worker and select() in parent process This allows us to pass results larger than PIPE_BUF through the pipes without interleaving them. This is necessary now because "hg fix" sends file contents as the result from workers. Differential Revision: https://phab.mercurial-scm.org/D3960

tests: refactor common bundle2 capabilities Differential Revision: https://phab.mercurial-scm.org/D1945

debug: move extensions debug behind a dedicated flag Since b86664c81833, we process the `--debug` flag earlier. This is overall good and useful, but has at least one negative side effect. Previously the debug message we report when trying to import extensions were issued before we processed the `--debug` flag. Now they happen after. Before: $ ./hg id --debug 21f507b8de2f9c1606e9aeb5ec7d2a6dedb7a4a7 tip After: $ ./hg id --debug ☿ (revset-bench) could not import hgext.evolve (No module named evolve): trying hgext3rd.evolve could not import hgext.mercurial_keyring (No module named mercurial_keyring): trying hgext3rd.mercurial_keyring could not import hgext3rd.mercurial_keyring (No module named mercurial_keyring): trying mercurial_keyring could not import hgext.hggit (No module named hggit): trying hgext3rd.hggit could not import hgext3rd.hggit (No module named hggit): trying hggit 21f507b8de2f9c1606e9aeb5ec7d2a6dedb7a4a7 tip (This get worse if --traceback is used). To work around this, we move this extensions related debug message behind a new flag 'devel.debug.extensions' and restore the previous output. I'm not fully happy about using the 'devel' section for a flag that can be used by legitimate users to debug extensions issues. However, it fits well next to other `devel.devel.*` options and is mostly used by extensions author anyway. We might move it to another, more appropriate section in the future (using alias).

curses: use "text" interface if TERM=dumb Differential Revision: https://phab.mercurial-scm.org/D3948

windows: expand '~/' and '~\' to %USERPROFILE% when translating to cmd.exe It's convenient to be able to reference hooks in a portable location on any platform.

windows: replace single quote with double quote when translating to cmd.exe Since cmd.exe doesn't understand single quotes, single quotes to prevent $var expansion is basically unusable without this. Single quote isn't allowed in a path name, so it seems unlikely to come up otherwise.

hook: only print the note about native cmd translation if it actually changes This makes it so that it will never occur on a non Windows platform.

hook: disable the shell to native command translation by default There are other things I want to add like ~ expansion and translating single to double quotes for cmd.exe. So off by default is safer. I'm having second thoughts about the name, but I don't have any better ideas.