gitRepo: Rewrite the "urllib.request.urlopen" patch for Python 3

The old variant is still working but setting "cafile" is deprecated
since version 3.6 [0] and generates a warning:
DeprecationWarning: cafile, capath and cadefault are deprecated, use a custom context instead.

But without this patch "fetchRepoProject" still fails with
"error no host given" (see 337380ea).

[0]: https://docs.python.org/3.7/library/urllib.request.html#urllib.request.urlopen