merge: fix a copy detection bug (issue672) When merging rev1 and rev2, we want to search for copies that happened in rev1 but not in rev2 and vice-versa. We were starting the search at rev1/rev2 and then going back, stopping as soon as we reached the revno of the ancestor, but that can miss some cases (see the new test-issue672). Now we calculate the revisions that are ancestors of rev1 or rev2 (but not both) and make sure the search doesn't stop too early. Simplified test provided by mpm, based on a test case provided by Edward Lee.

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Should display 'First commit message'
description:
First commit message



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Should display 'Second commit message'
description:
Second commit message



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Should display 'Third commit message\n This is the 3rd log message'
description:
Third commit message
 This is the 3rd log message



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Should display 'Fifth commit message\n This is the 5th log message'
description:
Fifth commit message