tests/test-dirstate-backup.t

sparse: --include 'dir1/dir2' should not include 'dir1/*'

In 2015 there was a workaround added (f39bace2d6cad32907c0d7961b3c0dbd64a1b7ad)
to sparse in the hg-experimental repo. That workaround:
a) no longer seems to be needed, since its testcase passes even with the code
   removed, and
b) caused a new problem: --include 'dir1/dir2' ended up including dir1/*
   too. (--include 'glob:dir1/dir2' is a user-level workaround.)

Remove the offending code, and add a testcase for situation B.

Set up

  $ hg init repo
  $ cd repo

Try to import an empty patch

  $ hg import --no-commit - <<EOF
  > EOF
  applying patch from stdin
  abort: stdin: no diffs found
  [255]

No dirstate backups are left behind

  $ ls .hg/dirstate* | sort
  .hg/dirstate