testrunner: on error, color the "(case xxx)" part the same as filename When using #testcases, the lines that read something like ERROR: test-split.t (case obsstore-off) output changed get colored red and the filename gets highlighted with a brighter red. This makes it harder to notice the "case obsstore-off" part, but it does seem important, so let's highlight it. Differential Revision: https://phab.mercurial-scm.org/D1959