Can't load '.'

[Zitrax]

Currently when trying to load tests from name '.' we had a platform difference since it cause use of absolute path which in turn cause us to split on ':' on windows while linux does not have a ':' in the path.

This is currently worked around / disabled by returning an empty test suite if '.' is used.

Obviously this should be handled better by actually loading tests properly.

The workaround was added in 2abbf4e.