util: fix url.__str__() for windows file URLs
Before:
>>> str(url('file:///c:/tmp/foo/bar'))
'file:c%3C/tmp/foo/bar'
After:
>>> str(url('file:///c:/tmp/foo/bar'))
'file:///c%3C/tmp/foo/bar'
The previous behaviour had no effect on mercurial itself (clone command for
instance) because we fortunately called .localpath() on the parsed URL.
hgsubversion was not so lucky and cloning a local subversion repository on
Windows no longer worked on the default branch (it works on stable because
de7e2fba4326 defeats the hasdriveletter() test in url class).
I do not know if the %3C is correct or not but svn accepts file:// URLs
containing it. Mads fixed it in
de7e2fba4326, so we can always backport should
the need arise.