CONTRIBUTORS

windows: add a method to convert Unix style command lines to Windows style

This started as a copy/paste of `os.path.expandvars()`, but limited to a given
dictionary of variables, converting `foo = foo + bar` to `foo += bar`, and
adding 'b' string prefixes.  Then code was added to make sure that a value being
substituted in wouldn't itself be expanded by cmd.exe.  But that left
inconsistent results between `$var1` and `%var1%` when its value was '%foo%'-
since neither were touched, `$var1` wouldn't expand but `%var1%` would.  So
instead, this just converts the Unix style to Windows style (if the variable
exists, because Windows will leave `%missing%` as-is), and lets cmd.exe do its
thing.

I then dropped the %% -> % conversion (because Windows doesn't do this), and
added the ability to escape the '$' with '\'.  The escape character is dropped,
for consistency with shell handling.

After everything seemed stable and working, running the whole test suite flagged
a problem near the end of test-bookmarks.t:1069.  The problem is cmd.exe won't
pass empty variables to its child, so defined but empty variables are now
skipped.  I can't think of anything better, and it seems like a pre-existing
violation of the documentation, which calls out that HG_OLDNODE is empty on
bookmark creation.

Future additions could potentially be replacing strong quotes with double quotes
(cmd.exe doesn't know what to do with the former), escaping a double quote, and
some tilde expansion via os.path.expanduser().  I've got some doubts about
replacing the strong quotes in case sh.exe is run, but it seems like the right
thing to do the vast majority of the time.  The original form of this was
discussed about a year ago[1].

[1] https://www.mercurial-scm.org/pipermail/mercurial-devel/2017-July/100735.html

[This file is here for historical purposes, all recent contributors
should appear in the changelog directly]

Andrea Arcangeli <andrea at suse.de>
Thomas Arendsen Hein <thomas at intevation.de>
Goffredo Baroncelli <kreijack at libero.it>
Muli Ben-Yehuda <mulix at mulix.org>
Mikael Berthe <mikael at lilotux.net>
Benoit Boissinot <bboissin at gmail.com>
Brendan Cully <brendan at kublai.com>
Vincent Danjean <vdanjean.ml at free.fr>
Jake Edge <jake at edge2.net>
Michael Fetterman <michael.fetterman at intel.com>
Edouard Gomez <ed.gomez at free.fr>
Eric Hopper <hopper at omnifarious.org>
Alecs King <alecsk at gmail.com>
Volker Kleinfeld <Volker.Kleinfeld at gmx.de>
Vadim Lebedev <vadim at mbdsys.com>
Christopher Li <hg at chrisli.org>
Chris Mason <mason at suse.com>
Colin McMillen <mcmillen at cs.cmu.edu>
Wojciech Milkowski <wmilkowski at interia.pl>
Chad Netzer <chad.netzer at gmail.com>
Bryan O'Sullivan <bos at serpentine.com>
Vicent Seguí Pascual <vseguip at gmail.com>
Sean Perry <shaleh at speakeasy.net>
Nguyen Anh Quynh <aquynh at gmail.com>
Ollivier Robert <roberto at keltia.freenix.fr>
Alexander Schremmer <alex at alexanderweb.de>
Arun Sharma <arun at sharma-home.net>
Josef "Jeff" Sipek <jeffpc at optonline.net>
Kevin Smith <yarcs at qualitycode.com>
TK Soh <teekaysoh at yahoo.com>
Radoslaw Szkodzinski <astralstorm at gorzow.mm.pl>
Samuel Tardieu <sam at rfc1149.net>
K Thananchayan <thananck at yahoo.com>
Andrew Thompson <andrewkt at aktzero.com>
Michael S. Tsirkin <mst at mellanox.co.il>
Rafael Villar Burke <pachi at mmn-arquitectos.com>
Tristan Wibberley <tristan at wibberley.org>
Mark Williamson <mark.williamson at cl.cam.ac.uk>