githelp: vendor Facebook authored extension This commit vendors the Facebook-authored "githelp" extension. This extension provides a "githelp" command that can be used to try to convert a `git` command to its Mercurial equivalent. This functionality is useful for Git users learning Mercurial. The extension was copied from the repository at revision 32ceeccb832c433b36e9af8196814b8e5a526775. The following modifications were made: * The "testedwith" value has been changed to match core's conventions. * Support for a custom footer has been removed, as it is Facebook specific. The feature is useful. But the implementation wasn't appropriate for core. * A test referencing "tweakdefaults" has been removed. * Imports changed to match Mercurial's style convention. * Double newlines in test removed. * Pager activation changed to ui.pager(). * Initial line of githelp.py changed to add description of file. The removal of the custom footer code was the only significant source change. The rest were mostly cosmetic. There are still some Facebook-isms in the extension. I'll address these as follow-ups. .. feature:: githelp extension The "githelp" extension provides the ``hg githelp`` command. This command attempts to convert a ``git`` command to its Mercurial equivalent. The extension can be useful to Git users new to Mercurial. Differential Revision: https://phab.mercurial-scm.org/D1722

--- a/tests/test-help.t	Thu Jan 18 19:40:17 2018 +0530
+++ b/tests/test-help.t	Mon Dec 18 20:44:59 2017 -0800
@@ -261,6 +261,7 @@
        eol           automatically manage newlines in repository files
        extdiff       command to allow external programs to compare revisions
        factotum      http authentication with factotum
+       githelp       try mapping git commands to Mercurial commands
        gpg           commands to sign and verify changesets
        hgk           browse the repository in a graphical way
        highlight     syntax highlighting for hgweb (requires Pygments)