The subversion tests used different tricks to create properly encoded URLs,
partly due to partial support for different ways of running the tests on
windows. Now we only need/support one way of running the tests on windows.
Windows URLs should look like 'file:///c:/foo%20bar' and on Unix platforms
like 'file:///tmp/baz'.
'pwd' in the test framework will on Windows emit paths like 'c:/foo bar'.
Explicit handling of backslashes in paths is thus no longer needed and is
removed. Paths on windows do however need an extra '/' compared to other
platforms.
This change makes test-subrepo-svn.t pass on windows with msys. Other tests
might need more work.
