tests/test-diff-newlines.t

templates: make earlycommands and othercommands optional

We now have sub-topics in the help system. The "helptopics" template
serves as a mechanism for displaying an index of help topics.
Previously, it was only used to show the top-level list of help topics,
which includes special groupings of topics.

In the near future, we'll adapt "helptopics" for showing the index
of sub-topics. In this patch, we optionally render {earlycommands} and
{othercommands} since they aren't present on sub-topics.

  $ hg init

  $ $PYTHON -c 'file("a", "wb").write("confuse str.splitlines\nembedded\rnewline\n")'
  $ hg ci -Ama -d '1 0'
  adding a

  $ echo clean diff >> a
  $ hg ci -mb -d '2 0'

  $ hg diff -r0 -r1
  diff -r 107ba6f817b5 -r 310ce7989cdc a
  --- a/a	Thu Jan 01 00:00:01 1970 +0000
  +++ b/a	Thu Jan 01 00:00:02 1970 +0000
  @@ -1,2 +1,3 @@
   confuse str.splitlines
   embedded\r (no-eol) (esc)
  newline
  +clean diff