Fix a lurking unicode string in get_repository_info() for specifying the

default base_path.  This could cause a crash in convert_to_absolute_paths()

when joining with a filename containing non-UTF8 characters.  This case was

only accessible when the --repository-url option was specified.
Added a new test case to exercise this bug, and it failed as expected before the

fix was introduced.  Since this case requires --repository-url it is necessary

to update the testdata repository to contain a file with a non-UTF8 filename.

Thus, I introduced revision 4 to the repo which adds a single file with a non-UTF8

character in both its name and file contents.
Causing HEAD of the testrepo to advance to r4 in turn caused the existing

test_diff_exclude() test to fail.  This is because this test was modifying

foo.txt, which is already in the repo, which causes the diff signature to

change to indicate revision 4 versus 3.  This is the only test case that has a

dependency on the current HEAD revision number, so to prevent this regression

from occurring again in the future, I altered the test to add a new new file

(bar.txt) rather than modifying an existing file.  This change in approach

does not impact the underlying purpose of the test.  Note, since the diff

signature for file additions varies between SVN client versions the decorator is

now utilized to generate the correct MD5 hash.

Ran all unit tests under both SVN 1.6.23 and 1.7.14.