bug#17859: tramp-test31-utf8 aborts

[Glenn Morris]

Package: emacs
Version: 24.4.50

Current trunk on x86_64 RHEL 6.5. tramp-test31-utf8 aborts (in that ert
aborts the test, not that it makes Emacs abort):

A tramp-test31-utf8
    Check UTF8 encoding in file names and file contents.
    aborted

I'm not sure how to get useful information out of it.
`b' doesn't show a proper backtrace. I get:

cond: Wrong method specification for `mock'
ert-results-pop-to-backtrace-for-test-at-point: cl-etypecase failed:
[cl-struct-ert-test-aborted-with-non-local-exit  (((skip-unless
(tramp--test-enabled)) :form (tramp--test-enabled) :value t) ((should
(file-exists-p file1)) :form (file-exists-p
/mock:host.name.removed:/tmp/tramp-test15919jlp/<arabic text>) :value
t))], (ert-test-passed ert-test-result-with-condition)