tests: add magic string to bypass check-commit Allow bypassing test-check-commit runs by specifying '# no-check-commit' in the description. This should be avoided but is useful for upstream imports such as pywatchman which will cause check-code to fail otherwise.

demandimport: do not raise ImportError for unknown item in fromlist This is the behavior of the default __import__() function, which doesn't validate the existence of the fromlist items. Later on, the missing attribute is detected while processing the import statement. https://hg.python.org/cpython/file/v2.7.13/Python/import.c#l2575 The comtypes library relies on this (maybe) undocumented behavior, and we got a bug report to TortoiseHg, sigh. https://bitbucket.org/tortoisehg/thg/issues/4647/ The test added at 26a4e46af2bc verifies the behavior of the import statement, so this patch only adds the test of __import__() function and works around CPython/PyPy difference.

convert: config option for git rename limit By default, Git applies rename and copy detection to 400 files. The diff.renamelimit config option and -l argument to diff commands can override this. As part of converting some repositories in the wild, I was hitting the default limit. Unfortunately, the warnings that Git prints in this scenario are swallowed because the process running functionality in common.py redirects stderr to /dev/null by default. This seems like a bug, but a bug for another day. This commit establishes a config option to send the rename limit through to `git diff-tree`. The added tests demonstrate a too-low rename limit doesn't result in copy metadata being recorded.