Make skip_empty have an effect on XML reporting

[ilkecan]

Is your feature request related to a problem? Please describe.
It seems setting skip_empty to True in .coveragerc has no effect on XML reporting.

Describe the solution you'd like
I would like setting skip_empty to True to actually skip the empty files during XML reporting.

Describe alternatives you've considered
I can currently omit the empty files, but this not very convenient.

Additional context
I have empty __init__.py files in my project (they are actually only created because Coverage.py requires them to include un-tested files in those directories in the report.) and when I generate an XML report while skip_empty is set to True, those empty files are also in the report. As a result, cobertura plug-in in Jenkins shows wrong results (this might be unrelated).

[nedbat]

This is fixed in 97f05c9

[nedbat]

This is now released as part of coverage 5.2.