Diff at end of commit message

[Stefan Schwarzer]

When I commit a change, I edit the commit message in the
editor. Inside the editor, I like a diff of the changes
that are about to be committed.

I found out that I can set a template for the commit
message in my Mercurial configuration file under
`[committemplate]`. At the moment, I use

[committemplate]
changeset = {desc}\n
    HG: Enter commit message.  Lines beginning with 'HG:' are removed.
    HG: {extramsg}
    HG: --
    HG: user: {author}\n{ifeq(p2rev, "-1", "",
   "HG: branch merge\n")
   }HG: branch '{branch}'\n{if(activebookmark,
   "HG: bookmark '{activebookmark}'\n")   }{subrepos %
   "HG: subrepo {subrepo}\n"              }{file_adds %
   "HG: added {file}\n"                   }{file_mods %
   "HG: changed {file}\n"                 }{file_dels %
   "HG: removed {file}\n"                 }{if(files, "",
   "HG: no files changed\n")}
   HG: ------------------------ >8 ------------------------
   HG: Do not touch the line above.
   HG: Everything below will be removed.
   {diff()}

which I took from the `hgrc` manpage and added the `{diff()}`
at the end.

I have two questions:

- What I'd ideally like would be the "default commit template"
  for the version of Mercurial plus the `diff` call. This means
  if I update to a new Mercurial version, the then-current
  default commit template (possibly depending on special
  situations like merges) should be used, plus the diff. Is
  there a way to achieve this?

- I noticed that the above template also includes binary diffs.
  Usually these aren't useful. Is there a way to let `{diff()}`
  or a similar placeholder only contain text changes?

Best regards,
Stefan