Reland again Msysgit Support for gcl and git-cl....

Reland again Msysgit Support for gcl and git-cl.

EDITOR environment variable shouldn't be required anymore
can contain quotes and multiple arguments.

Uses shell=True to let the shell parse the quoted string
instead of handling all forms of quotes ourselves. 

By default, msysgit ships with the TERM environment variable
set, when set to 'msys', we prepend 'env' to the executed
command. That is required so msys knows which program
to run the given file.

BUG=none
TEST=On many platforms. Win7, WinXP, Ubuntu.
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=78332

[Mohamed Mansour, 2011-03-14 20:22:52]

I will commit this "after" hours. Maybe around 10PM EST. When you have a chance,
please verify it will work on a Mac. If not, I will try remote desktop on my
friends Mac Pro after he finishes work and see if any problems persist.

So far it has been tested on:
 Win7 - Console (%TERM% unset, %EDITOR% unset)
 Win7 - Console (%TERM% = dumb, %EDITOR% unset)
 Win7 - Msysgit ($TERM = msys, $EDITOR=vim)
 Win7 - Msysgit ($TERM = msys, $EDITOR="vim +")
 Win7 - Cygwin ($TERM = dumb, $EDITOR unset)
 Win7 - Cygwin ($TERM = dumb, $EDITOR="vim")
 WinXP - Console (%TERM% unset, %EDITOR% unset)
 Ubuntu - Terminal (%TERM% = linux, %EDITOR%=vim)

[TVL, 2011-03-14 20:53:38]

http://codereview.chromium.org/6685062/diff/1/git_cl/git_cl.py
File git_cl/git_cl.py (right):

http://codereview.chromium.org/6685062/diff/1/git_cl/git_cl.py#newcode715
git_cl/git_cl.py:715: cmd = '%s %s' % (GetEditor(), filename)
um, GetEditor() doesn't exist in here, and there is a fetch into editor a few
lines above.

[Mohamed Mansour, 2011-03-14 20:58:17]

Copy fail :(

http://codereview.chromium.org/6685062/diff/1/git_cl/git_cl.py
File git_cl/git_cl.py (right):

http://codereview.chromium.org/6685062/diff/1/git_cl/git_cl.py#newcode715
git_cl/git_cl.py:715: cmd = '%s %s' % (GetEditor(), filename)
On 2011/03/14 20:53:38, TVL wrote:
> um, GetEditor() doesn't exist in here, and there is a fetch into editor a few
> lines above.

Done.

[Mohamed Mansour, 2011-03-15 00:37:03]

Please let me know if this is acceptable. I believe we handled all cases
possible :)

[TVL, 2011-03-15 11:55:23]

seems ok, but M-A is the expert.

[M-A Ruel, 2011-03-15 17:09:46]

lgtm