While implementing a test for pytest-dev/pytest-forked#33 I've hit this:

INTERNALERROR>   File "~/src/github/pytest-dev/pytest-forked/.tox/py27-pytest46/lib/python2.7/site-packages/_pytest/terminal.py", line 190, in pytest_report_teststatus
INTERNALERROR>     return report.outcome, letter, report.outcome.upper()
INTERNALERROR> UnboundLocalError: local variable 'letter' referenced before assignment

Looking at the repo, it seems to have been fixed on master by @nicoddemus as a part of #6337. But it still persists in the 4.6.x branch.

The fix should be trivial: just add a fallback variable value before if-blocks. No need to backport that whole PR (unless somebody thinks that it should be done, of course).

Ref: #7311.