In commit v3.7.0-rc1~158^2 (ExternalData: Tolerate files duplicated
across multiple targets, 2016-07-07) we added a test case for repeating
the same data file reference in three different targets in the same
directory in order to exercise its corresponding fix. However, we
re-used the top-level `Data.dat` file which is already produced by
an unrelated test case. `ninja` diagnoses the duplicate rule.
Update the test to use a dedicated data file name for the three-times
repeated case to avoid this conflict. It still covers the original
purpose of the test.
bb66cea6c5