Steps to replicate the issue (include links if applicable):

• Open the history of a Wikidata Item (presumably this also happens with Properties and Lexemes but I only tested Items) like https://www.wikidata.org/w/index.php?title=Q4115189&action=history
• Select two non-consecutive revisions with the radio buttons and press "Compare selected revisions"
• Press "undo"
• Press "Publish Changes" to undo the edits

What happens?:
The edit summary will say that you only undid the last edit even though you undid all the edits between the two revisions. See an example.

What should have happened instead?:
The edit summary should say that you undid multiple revisions. This is what happens when undo is used in a regular MediWiki page such as this one.

Software version (on Special:Version page; skip for WMF-hosted wikis like Wikipedia):

Other information (browser name/version, screenshots, etc.):
Apparently undoing Wikibase Mediainfo edits on Commons does not generate an automated summary at all so the bug does not affect that site.