In Message, respect Content-Type provided by the user

* lisp/gnus/mml.el (mml-parse-1): Respect any Content-Type
inserted by the user instead of insisting on text/plain.
1 job for master in 55 minutes and 42 seconds (queued for 1 second)
Status Job ID Name Coverage
failed #2365


Name Stage Failure
test-all Test
Makefile:318: recipe for target 'check-doit' failed
make[2]: *** [check-doit] Error 1
make[2]: Leaving directory '/builds/emacs/emacs/test'
make[1]: *** [check-expensive] Error 2
Makefile:293: recipe for target 'check-expensive' failed
make[1]: Leaving directory '/builds/emacs/emacs/test'
Makefile:959: recipe for target 'check-expensive' failed
make: *** [check-expensive] Error 2
ERROR: Job failed: exit code 1