Merge branch 'maint'

* maint:
  Update release notes for 1.6.0.3
  Teach rebase -i to honor pre-rebase hook
  docs: describe pre-rebase hook
  do not segfault if make_cache_entry failed
  make prefix_path() never return NULL
  fix bogus "diff --git" header from "diff --no-index"
  Fix fetch/clone --quiet when stdout is connected
  builtin-blame: Fix blame -C -C with submodules.
  bash: remove fetch, push, pull dashed form leftovers

Conflicts:
	diff.c

diff.c

@@ -1509,6 +1509,10 @@ static void builtin_diff(const char *name_a,
 		b_prefix = o->b_prefix;
 	}
 
+	/* Never use a non-valid filename anywhere if at all possible */
+	name_a = DIFF_FILE_VALID(one) ? name_a : name_b;
+	name_b = DIFF_FILE_VALID(two) ? name_b : name_a;
+
 	a_one = quote_two(a_prefix, name_a + (*name_a == '/'));
 	b_two = quote_two(b_prefix, name_b + (*name_b == '/'));
 	lbl[0] = DIFF_FILE_VALID(one) ? a_one : "/dev/null";