Lost this somehow in refactoring, but right now failed commands are silent.
Raise an exception and print the error details.
Restore behaviour where we can print command output on success if desired.
Fix a couple tests that were actually failing due to missing rsync dest.
before this commit: fetch_tests and release_yum_tests
allow *any* dist tag, but the tag must not be empty or
else the glob fails on double-dot in path name.
after this commit: allow the tag to be any *or* empty.
python3 does not allow relative imports.
test/unit/__init.py__ and test/functional/__init.py__ already exist,
which means we can use absolute import on all versions of python
without resorting to http://legacy.python.org/dev/peps/pep-0328/
Add modules compat lib to support both python 2 and 3, and
add unit test to detect regressions.
Tito uses two modules that have changed significantly between
python 2 and 3:
* commands module merged into subprocess module
* ConfigParser module renamed as configparser
