Comment 10 for bug 1812955

Finally bisected. It seems like a regression in upstream mutter master this week:

1bbb5c8107ab77435f97c1b037a89a76121f6e3c is the first bad commit
commit 1bbb5c8107ab77435f97c1b037a89a76121f6e3c
Author: Jonas Ådahl <email address hidden>
Date: Sun Jan 20 17:41:53 2019 +0100

    meta: Only declare types when generating gir files

    Some types were declared in the public headers so that g-ir-scanner
    could resolve the types. This caused warnings when using
    -Wredundant-decls, so only redeclare them for the gir scanner.

:040000 040000 4ae3c1d894a568cf0903696034af467698403bc8 d32098d7d43859454dcc33c99f56e63e05a0fb03 M src

So not an Ubuntu bug.