view hgext/__init__.py @ 21199:e9c2f76be74b stable

help: clarify distinction among `contains`/`file`/`filelog`

For a Mercurial new-comer, the distinction between `contains(x)`,
`file(x)`, and `filelog(x)` in the "revsets" help page may not be
obvious. This commit tries to make things more obvious (text based on
an explanation from Matt in an FB group thread).

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