commitctx: gather more preparation code within the lock context
This is a small change that exist mostly for clarification. I am about to move a
large amount of code in its own function. having all that code next to each
other will make the next changeset clearer.
#require emacs
$ emacs -q -no-site-file -batch -l $TESTDIR/../contrib/hg-test-mode.el \
> -f ert-run-tests-batch-and-exit
Running 1 tests (*) (glob)
passed 1/1 hg-test-mode--compilation-mode-support
Ran 1 tests, 1 results as expected (*) (glob)