match: strengthen visit_children_set invariant, Recursive means "all files" My previous interpretation of "Recursive" was too relaxed: I thought it instructed the caller to do something like this: > you can stop calling `visit_children_set` because you'll need to descend into > every directory recursively, but you should still check every file if it > matches or not Whereas the real instruction seems to be: > I guarantee that everything in this subtree matches, you can stop > querying the matcher for all files and dirs altogether. The evidence to support this: - the test actually passes with the stronger invariant, revealing no exceptions from this rule - the implementation of `visit_children_set` for `DifferenceMatcher` clearly relies on this requirement, so it must hold for that not to lead to bugs.

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  $ hg init

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  $ echo 123 > a

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  $ hg add a

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  $ hg commit -m "first" a

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  $ mkdir sub

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  $ echo 321 > sub/b

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  $ hg add sub/b

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  $ hg commit -m "second" sub/b

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  $ cat sub/b

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  321

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  $ hg co 0

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  0 files updated, 0 files merged, 1 files removed, 0 files unresolved

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  $ cat sub/b 2>/dev/null || echo "sub/b not present"

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  sub/b not present

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  $ test -d sub || echo "sub not present"

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  sub not present

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