Dependencies included using relative paths are not de-duped correctly, causing modal Visual Studio warnings

What steps will reproduce the problem?
1. Assume you have ./module1/dependency, ./module1/component1, and 
./module2/component2 in your project. 
2. In the .gyp file for ./module1/component1, add a dependency on 
"../dependency/dependency.gyp:*".
3. In the .gyp file for ./module2/component2, add a dependency on 
"../../module1/dependency/dependency.gyp:*".
4. Run gyp to generate a MS Visual Studio solution (2005 or 2008) and then 
open the top-level solution in MSVS.

What is the expected output? What do you see instead?
Expected: Visual Studio happily loads the solution.
Actual: Visual Studio pops up a warning about "dependency" being a 
duplicate project because both "../dependency" and 
"../../module1/dependency" are present in the .sln file despite referring 
to the same project. I can work around this by changing the path in 
component1's gyp file to match the (more indirect) path in component2's 
.gyp file. (i.e. use "../../module1/dependency" even from within module1)

What version of the product are you using? On what operating system?
Revision 813 on Windows Vista/Windows 7 + Visual Studio 2005 
Professional/Visual Studio 2008 Team Suite.

Please provide any additional information below.

Original issue reported on code.google.com by sblom...@gmail.com on 21 Apr 2010 at 6:06

nminhtu94 / gyp

Dependencies included using relative paths are not de-duped correctly, causing modal Visual Studio warnings #151