The command cache should not cache commands in different .gyp files

[GoogleCodeExporter]

What steps will reproduce the problem?
1. Create a .gyp file in directory A that includes its sources using: 
'sources': ['<!@(ls *.cc)']
2. Create a .gyp file in directory B that includes its sources using: 
'sources': ['<!@(ls *.cc)']
3. Create a .gyp file that depends on the first two .gyp files

What is the expected output? What do you see instead?
Expected: The sources of 1 and 2 should be different.
Actual: The sources of 1 and 2 are the same due to the ls *.cc command being 
cached, despite a different CWD.

What version of the product are you using? On what operating system?
OSX Lion, GYP revision 1393 (head as of May 25, 2012)

Please provide any additional information below.

Original issue reported on code.google.com by agri...@google.com on 25 May 2012 at 4:00

[GoogleCodeExporter]

Not sure how to close this, but it's a dupe of 
http://code.google.com/p/gyp/issues/detail?id=112

Original comment by agri...@google.com on 11 Oct 2012 at 7:03