Commit 606b783acb leverages a 2015 hack that extracts the
package version from the buffer file name, only he has to
explicitly `set-visited-file-name` to do it.

`set-visited-file-name` has the adverse side effect of
changing the default-directory, and that causes me problems.

If the ostensible reason for bug#48137 was to get the "lm"
functions dos-aware, then why not do that instead of applying
a workaround on top of a hack?