histedit: render a rolled up description using the proper roll colours
Users have rightfully complained that the old behaviour of completely
removing the description of a rolled commit makes it difficult to
remember what was in that commit. Instead, we now render the removed
description in red.
I couldn't think of a simpler way to do this. You can't just combine
existing curses colours into new effects; only secondary effects like
bold or underline can be logically OR'ed to generate a combined text
effect. It seems easier to just redundantly keep track of what the
roll colour should be.
#
# Avoid interference from actual test env:
unset HGTEST_JOBS
unset HGTEST_TIMEOUT
unset HGTEST_PORT
unset HGTEST_SHELL