patch: improve heuristics to not take the word "diff" as header (issue1879) The word "diff" is likely to appear in a commit message. Let's make it less likely by requiring "diff -" for "diff -r" or "diff --git".

rebase: drop --style option It existed from the very start, but I don't think the rebase command does support log-like templates.

run-tests: $TESTDIR can be something else than $PWD $TESTDIR is expected to be the directory were the test lives, and is often used to reference helper functions. However, it is now set to $PWD at test invocation time, so if `run-tests.py` is called from another folder, the test will fail. The solution is to force $TESTDIR to be the base directory of the test itself, irrespective of where the runner is called from.