multimail/p4: issues identified by lgtm.com

Hi team,

while Coverity was down (it still is not reachable for me, but I guess that's just because everybody and their dog wants to catch up on a month of work delayed by their outage), I tried to find alternatives, and one of them is lgtm.com. Their C/C++ support is not generally available yet, but there have been a couple of issues identified in our Python scripts:

https://lgtm.com/projects/g/git/git/alerts/?mode=list&rule=py%2Fcall%2Fwrong-arguments%2Cpy%2Fcall%2Fwrong-named-argument%2Cpy%2Fexplicit-call-to-delete%2Cpy%2Finconsistent-equality%2Cpy%2Finheritance%2Fincorrect-overridden-signature%2Cpy%2Fmissing-call-to-init%2Cpy%2Fmultiple-definition%2Cpy%2Fredundant-else%2Cpy%2Funinitialized-local-variable%2Cpy%2Funreachable-statement

From a cursory look, it *does* seem as if there are legitimate issues there that want to be fixed ;-) But then, I am far from a Python expert, so my impressions could be completely off the mark.

Ciao, Johannes