utils.py: read_wikiversions handle FORCE_MW_VERSION
If utils.read_wikiversions()
finds FORCE_MW_VERSION
set in the
environment, it will use that as the version for all wikis found in
wikiversions.json, regardless of what version is actually in the file.
For example:
$ FORCE_MW_VERSION=1.23.4-wmf.0 scap wikiversions-inuse
1.23.4-wmf.0
Bug: T369115