tests: fix test results for 07faba78cf5a

tests/test-diff-unified.out

@@ -1,49 +1,58
 adding a
 % default context
 diff -r cf9f4ba66af2 a
 --- a/a
 +++ b/a
 @@ -2,7 +2,7 @@
  c
  a
  a
 -b
 +dd
  a
  a
  c
 % invalid --unified
 abort: diff context lines count must be an integer, not 'foo'
 % --unified=2
 diff -r cf9f4ba66af2 a
 --- a/a
 +++ b/a
 @@ -3,5 +3,5 @@
  a
  a
 -b
 +dd
  a
  a
 % diff.unified=2
 diff -r cf9f4ba66af2 a
 --- a/a
 +++ b/a
 @@ -3,5 +3,5 @@
  a
  a
 -b
 +dd
  a
  a
 % diff.unified=2 --unified=1
 diff -r cf9f4ba66af2 a
 --- a/a
 +++ b/a
 @@ -4,3 +4,3 @@
  a
 -b
 +dd
  a
 % invalid diff.unified
 abort: diff context lines count must be an integer, not 'foo'
+% test off-by-one error with diff -p
+adding a
+diff -r cb9a9f314b8b a
+--- a/a	Thu Jan 01 00:00:00 1970 +0000
++++ b/a	Thu Nov 27 17:46:15 2008 +0000
+@@ -1,0 +1,1 @@
++b
+@@ -2,0 +3,1 @@ a
++c