use __contains__, index or split instead of str.find
str.find return -1 when the substring is not found, -1 evaluate
to True and is a valid index, which can lead to bugs.
Using alternatives when possible makes the code clearer and less
prone to bugs. (and __contains__ is faster in microbenchmarks)
adding a
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
adding b
pushing to ../a
abort: could not lock repository ../a: Permission denied