Comma in tag search seems to completely break the query logic

[afontenot]

Asking about this here because I'm not 100% confident this is an issue.

I noticed that searching for a comma in a tag seems to break the search parsing. I say "broken" because the resulting behavior is not self-consistent; in my tests the search will return all files even if you invert the tag search with a "^". If I comma was causing some sort of unfamiliar expected behavior that results in returning all files, then inverting the search should return no files. But this isn't the case, which leads me to suspect a parsing issue.

I'm on Beets 2.7.1.

$ beet ls | wc -l
6049
$ beet ls 'some random text' sometag:xxx, | wc -l
6049
$ beet ls 'some random text' ^sometag:xxx, | wc -l
6049
$ beet ls ^sometag:xxx, | wc -l
6049
$ beet ls 'some random text' ^sometag:'xxx,' | wc -l
6049
$ beet ls 'some random text' ^sometag::'xxx,' | wc -l
6049

Here is a sample query, you can see that the comma gets dropped from the actual query.

$ beet -v ls sometag:'xxx,' 2>&1 | grep 'Parsed query'
Parsed query: OrQuery([AndQuery([SubstringQuery('sometag', 'xxx', fast=False)]), AndQuery([TrueQuery()])])

What I was actually trying to do: come up with a query for (a) any track with no genre tag, and (b) any track with multiple genres tagged. So far I haven't figured out how to do that, there seem to be other issues (?) in searching for a blank genre tag (^$ doesn't work).