tests/test-diff-reverse.t

patch: fix fuzzing of hunks without previous lines (issue3264)

When applying hunks such as:

  @@ -2,1 +2,2 @@
   context
  +change

fuzzing would empty the "old" block and make patchfile.apply() traceback.
Instead, we apply the new block at specified location without testing.

The "bottom hunk" test was removed as patch(1) has no problem applying hunk
with no context in the middle of a file.

  $ hg init

  $ cat > a <<EOF
  > a
  > b
  > c
  > EOF
  $ hg ci -Am adda
  adding a

  $ cat > a <<EOF
  > d
  > e
  > f
  > EOF
  $ hg ci -m moda

  $ hg diff --reverse -r0 -r1
  diff -r 2855cdcfcbb7 -r 8e1805a3cf6e a
  --- a/a	Thu Jan 01 00:00:00 1970 +0000
  +++ b/a	Thu Jan 01 00:00:00 1970 +0000
  @@ -1,3 +1,3 @@
  -d
  -e
  -f
  +a
  +b
  +c

  $ cat >> a <<EOF
  > g
  > h
  > EOF
  $ hg diff --reverse --nodates
  diff -r 2855cdcfcbb7 a
  --- a/a
  +++ b/a
  @@ -1,5 +1,3 @@
   d
   e
   f
  -g
  -h