rlog: fix parsing of multiple file revisions

The rlog parser was only fetching a single file revision because
some lines of code had the wrong indentation. These lines were
supposed to be part of a loop body but were only executed once.

Also rename a function which had a misleading name and docstring.
This function does in fact process the entire RCS revision history
of a given file, as opposed to just one entry of RCS revision history.

Found while testing ingestion of the GNU dino repository from
cvs.savannah.gnu.org/sources/dino