Add python 2.7.5 support on Windows. Not enabled by default.

Add python 2.7.5 support on Windows. Not enabled by default.

- Python2.7.5 will be installed only if DEPOT_TOOLS_PYTHON_275=1,
  otherwise 2.6 is installed.
- Eventually the default will be changed to install python 2.7.5
  for new users.
- Afterward, python 2.7.5 will be always installed when not detected
  and 2.6 will be ignored.

README.chromium contains the exact instructions how to recreate
python275_bin.zip that was committed independently.

I tested it on a vanilla Windows XP image and documented how to
install the VC90 CRT redistributable in that specific case in
README.chromium.

R=iannucci@chromium.org
BUG=241769, 257696
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=227961

[iannucci, 2013-10-07 23:50:59]

lgtm

https://codereview.chromium.org/26326002/diff/1/bootstrap/win/win_tools.bat
File bootstrap/win/win_tools.bat (right):

https://codereview.chromium.org/26326002/diff/1/bootstrap/win/win_tools.bat#n...
bootstrap/win/win_tools.bat:142: cscript //nologo //e:jscript "%~dp0unzip.js"
"%~dp0python275_bin.zip" "%WIN_TOOLS_ROOT_DIR%"
Is there a way for us to replace all of our bat files with javascript? Or would
that be slow?

https://codereview.chromium.org/26326002/diff/1/bootstrap/win/win_tools.bat#n...
bootstrap/win/win_tools.bat:145: call copy /y "%~dp0pylint.new.bat"
"%WIN_TOOLS_ROOT_DIR%\pylint.bat" 1>nul
Maybe create these before the directory so if we try to look for the existence
of the dir we know that these are already done too.

[M-A Ruel, 2013-10-08 00:55:52]

https://codereview.chromium.org/26326002/diff/1/bootstrap/win/win_tools.bat
File bootstrap/win/win_tools.bat (right):

https://codereview.chromium.org/26326002/diff/1/bootstrap/win/win_tools.bat#n...
bootstrap/win/win_tools.bat:142: cscript //nologo //e:jscript "%~dp0unzip.js"
"%~dp0python275_bin.zip" "%WIN_TOOLS_ROOT_DIR%"
On 2013/10/07 23:50:59, iannucci wrote:
> Is there a way for us to replace all of our bat files with javascript? Or
would
> that be slow?

It'd be fine but not overly excited.

https://codereview.chromium.org/26326002/diff/1/bootstrap/win/win_tools.bat#n...
bootstrap/win/win_tools.bat:145: call copy /y "%~dp0pylint.new.bat"
"%WIN_TOOLS_ROOT_DIR%\pylint.bat" 1>nul
On 2013/10/07 23:50:59, iannucci wrote:
> Maybe create these before the directory so if we try to look for the existence
> of the dir we know that these are already done too.

Right now the python.bat script is a way to inhibit being auto-upgraded. It
won't be true soon.

[M-A Ruel, 2013-10-10 17:57:25]

Committed patchset #1 manually as r227961.

[anatoly techtonik, 2014-02-05 10:46:14]

Why 2.7.5 and not 2.7.x?

[M-A Ruel, 2014-02-05 18:29:46]

On 2014/02/05 10:46:14, anatoly techtonik wrote:
> Why 2.7.5 and not 2.7.x?

I don't understand the question. The code is indeed 2.7.x compatible. But this
bootstrapping code was specifically installing 2.7.5.

[anatoly techtonik, 2014-02-05 20:19:52]

On 2014/02/05 18:29:46, M-A Ruel wrote:
> On 2014/02/05 10:46:14, anatoly techtonik wrote:
> > Why 2.7.5 and not 2.7.x?
> 
> I don't understand the question. The code is indeed 2.7.x compatible. But this
> bootstrapping code was specifically installing 2.7.5.

Why hardcode the environment variable to 2.7.5? Is there a problem with 2.7.6 or
any later version - why it is not called just 27 instead of 275?