GitRepository: remove unused properties WorkingCopyPath and WorkingCopySubdir
GitRepository: remove unused properties WorkingCopyPath and WorkingCopySubdir

They were introduced in e3fd6fec ("Started implementing 'command_oneline'.",
2009-07-01) but actually never used.

As the properties were never set, the code removed checking for != null
was dead. Remove it, too.

PKRoma/git-tfs,git-tfs/git-tfs