> Here's an alternative proposal.  It seems like almost all VCS backends
> we support provide a variant of a "log" command that shows the diffs
> together with the usual meta-data shown by "log".  Only RCS and CVS
> don't have such an option of "log", all the rest do (most of them via
> "log -p").
>
> So we could make this a subcommand of vc-log, more accurately
> vc-print-root-log, such that "C-u C-u C-x v L" will prompt for a
> revision ID, and display the information produced by such a "log -p"
> command (and fall back to displaying just the diffs for RCS and CVS).
>
> Does this sound better?

This is fine.  Here's a new patch that implements 'M-1 C-x v L'
to limit the log to one revision expanded with diff: