When check-webkit-style is run with moved files in svn 1.9, errors are thrown in Tools/Scripts/webkitpy/common/checkout/diff_parser.py due to an unexpected diff format.
<rdar://problem/29979693>
A note here, while this title is accurate, the original description of this issue is not. check-webkit-style outputs a number of unneeded lines when files are moved, but these unneeded lines do not cause errors. Bug 167164 was the bug which was causing the errors due to an unexpected diff format.