Improved doc and tests for guilt header.

Signed-off-by: Per Cederqvist <[email protected]>
Signed-off-by: Josef 'Jeff' Sipek <[email protected]>

Documentation/guilt-header.txt

@@ -18,7 +18,10 @@ Prints either the topmost patch's header or the header of a specified patch.
 -E::
 	Open the raw patch in an editor, instead of printing it.
 <patchname>::
-	Name of the patch.
+	Name of the patch. If a patch with exactly this name exists,
+	use it. Otherwise, treat the name as a regexp; if the regexp
+	matches a single patch, use it. Otherwise, list all matching
+	patch names to stderr and fail.
 
 Author
 ------

regression/t-028.out

@@ -56,3 +56,12 @@ Patch non-existant is not in the series
   remove
   mode
   patch-with-some-desc
+% guilt header de
+de does not uniquely identify a patch. Did you mean any of these?
+  mode
+  patch-with-some-desc
+% guilt header des
+blah blah blah
+
+Signed-off-by: Commiter Name <commiter@email>
+

regression/t-028.sh

@@ -35,4 +35,7 @@ shouldfail guilt header non-existant
 # patch name is a regexp that just happens to match an existing patch.
 shouldfail guilt header '.*'
 
+shouldfail guilt header de
+cmd guilt header des
+
 # FIXME: how do we check that -e works?