Refactor the function into an helper.
* bzrlib/tests/test_log.py:
(TestCaseForLogFormatter.make_commits_with_trailing_newlines):
Turned into a helper.
(TestShortLogFormatter.test_trailing_newlines)
(TestLongLogFormatter.test_trailing_newlines)
(TestLineLogFormatter.test_trailing_newlines)
(TestLongLogFormatterWithoutMergeRevisions.test_long_trailing_newlines):
Use the helper, notice the pattern :-/