cleanup: use any() instead of checking truthiness of temporary list
It was not immediately obvious to me, when first seeing this, why a list was
created. It needed a second look to understand that the purpose was to check
whether the condition is true for any of the parents. Using any() for that is
clearer.
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https://www.mercurial-scm.org/wiki/ContributingChanges
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273ce12ad8f1` will report some style violations on a very old commit).