An utility method which was in RacyGitTests has been moved to
RepositoryTestCase. Also the javadoc has been improved.
This method allows to wait long enough until the
filesystem-timer has advanced. This is useful when it has to
be guaranteed that two files modifications have different
modification timestamps.
Change-Id: I2ebd7cd7818feba6acffb3f835101d8fd281bd5a Signed-off-by: Christian Halstrick <christian.halstrick@sap.com>