Unreleased file handles

[theseion]

libgit2 hold on to the file handle for the pack file. This becomes a problem on Windows, where a file can only be (completely) deleted after all handles have been closed.

This may be a problem with objects that aren't properly freed. However, the pack file seems to be the only file with this problem, so the error might actually lie with libgit2 itself.

See:

• DeleteFile: https://msdn.microsoft.com/en-us/library/windows/desktop/aa363915(v=vs.85).aspx
• File security and access rights: https://msdn.microsoft.com/en-us/library/windows/desktop/aa364399(v=vs.85).aspx
• File attribute constants: https://msdn.microsoft.com/en-us/library/windows/desktop/gg258117(v=vs.85).aspx
• SetFileAttributes: https://msdn.microsoft.com/en-us/library/windows/desktop/aa365535(v=vs.85).aspx
• System error codes: https://msdn.microsoft.com/en-us/library/windows/desktop/ms681382(v=vs.85).aspx
• Find file handles by process on Windows: http://serverfault.com/questions/1966/how-do-you-find-what-process-is-holding-a-file-open-in-windows

[tinchodias]

Interesting. So, this is the reason of the failing tests in Win7.

[theseion]

That's one reason. The other one is that the DeleteFile function used by FilePlugin to delete files on Windows cannot delete files which have the read-only attribute set. I'm submitting a fix where i try to remove the read-only attribute by calling SetFileAttributes before calling DeleteFile.

[tinchodias]

Superb. Is the file handle that libgit2 holds to the pack file read-only?

[theseion]

Probably not. But I haven't had time to dig into libgit2 yet.