rust-changelog: removed now useless early conditional for NULL_REVISION...
rust-changelog: removed now useless early conditional for NULL_REVISION
Now that the underlying `RevlogEntry` returned for `NULL_REVISION` is
viable, it has become pointless to check NULL_REVISION several times,
even for performance: the check will be far more frequent than the benefit
of bailing earlier in the rare case where the requested revision is
`NULL_REVISION`.
This case is covered explicitly by the first assertion of
`test_data_from_rev_null`.
