Regression/crash when calling client.propget()

[chipx86]

We provide Subvertpy support in Review Board, and hit an issue that started cropping up as customers upgraded installs to Subvertpy 0.11.

Starting in 0.11, client.propget() triggers an eventual assertion in libsvn, seen on Subversion 1.9.7 and 1.14.0 (only two versions tested).

From our two CI environments:

On 1.9.7:

'subversion-1.9.7/subversion/libsvn_subr/dirent_uri.c' line 1595: assertion failed (! svn_path_is_url(relative))

On 1.14.0:

'subversion-1.14.0/subversion/libsvn_subr/dirent_uri.c' line 1634: assertion failed (! svn_path_is_url(relative))

The line of code was:

return self.client.propget('svn:keywords', path, None, revnum)

In this code, path was pre-normalized to an absolute path (file://-based in unit tests), but we also tried relative.

This issue isn't present in 0.10. This new line was added in 0.11:

target = py_object_to_svn_abspath(py_target, temp_pool);

We've worked around this by moving to new code processing proplist(). Notably, this function lacks the above path conversion. This works on 0.10 and 0.11.