My previous change for SVN path normalization didn't actually work as

well as I had thought. It was tested in the CI environment that

originally unveiled the problems we had with quoting behavior, but those

tests were performed against a svn+ssh:// URL rather than the

file:// URL that the patch was ultimately written against.
It turns out that these two types of URLs have different restrictions. A

file:// URL cannot use non-printable characters (character codes 0

through 31), even if escaped, whereas other URLs can.
This change updates our tests to check against both. We now check

character codes 32+ for file:// URLs and 0+ for others. We also

validate that non-printable character codes aren't provided in a file

path, catching errors before it hits Subversion.

Unit tests pass on Python 2.7 and 3.x (when applied to the release-4.0.x

branch).
Unit tests also pass with this patch in the CI environment.