Lars Ingebrigtsen <larsi@gnus.org> writes:

> Is this with "emacs -Q"?

Yes, and I apologize for not mentioning the fact!

> I tried to reproduce the issue by putting that string into a buffer
> and then saying `M-x compilation-mode RET', but was unable to -- it
> recognised the file name as a file name, excluding ERROR:.

It seems that something else (whitespace?) triggers the bug.  Please see
the attached compilation output, where it shows with `emacs -Q' and
subsequent `M-x compilation-mode RET'.

> Which is a revision that doesn't exist in the Emacs repo, so are you
> on an updated Emacs version?

Yes.  Further, I now pulled b78508696b, and can still see the bug.

Rudy