Correct optimization from 3464f5e77f34; add a test.
If there are two (or more) heads that point to the same .hgtags
node, we can safely skip parsing the file in all but the last head.
(In 3464f5e77f34, we were parsing the file in the first head and
skipping all the others.)
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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
=======================
Should display 'Fifth commit message\n This is the 5th log message'
description:
Fifth commit message