Hi,
The format of the version of MediaWiki releases to Wikimedia sites is
changing with the 1.27 release cycle.
Old format: 1.26wmf24
New format: 1.27.0-wmf.1
This affects the "generator" property of action=query&meta=siteinfo.
This is being done to bring the version numbers in compliance with the
semantic versioning standard[1]. See the Phabricator ticket for more
details[2]. This switch will happen with the 1.27.0-wmf.1 deployment,
which started today, and will reach all sites on Thursday, October 1.
Frameworks (like Pywikibot) that check the version number for
compatibility checking may need to be updated for the new format.
Apologies for the late notice.
[1]
http://semver.org/
[2]
https://phabricator.wikimedia.org/T67306
-- Legoktm