This produces slightly bad results when branches are in play, but
overall I think it's probably worthwhile. We might be able to do
better with branches somehow, but I haven't given it any thought.
The tests in test-annotate.t and test-import-git.t that relied on trailing
space in a file created by a here string is now masked by a literal 'EOL'
string that is removed.
This speeds up the in-memory version of debugbuilddag that I'm
working on considerably for the case where we want to build just
a 00changelog.i (for discovery tests, for instance).
There are a couple of test changes because node ids in tests
have changed.
The changes to the patch names in test-mq-qdelete.t were required
because they could collide with nodeid abbreviations and newly
actually do (patch "c" collides with id "cafe..." for patch "b").
Overwriting instead of appending to the file removes the [defaults]
section put into the file by run-tests.py.
It also defeats the --inotify option to run-tests.py.
(Nothing was broken yet, but the lack of -d "0 0" cause changeset
hashes to change unexpectedly in a test case I was editing.)
