added diff -c option (show change of revision X = diff -r X-1:X)

osc/commandline.py

@@ -1101,6 +1101,9 @@ Please submit there instead, or use --nodevelproject to force direct submission.
 
 
     @cmdln.alias('di')
+    @cmdln.option('-c', '--change', metavar='rev',
+                        help='the change made by revision rev (like -r rev-1:rev).'
+                             'If rev is negative this is like -r rev:rev-1.')
     @cmdln.option('-r', '--revision', metavar='rev1[:rev2]',
                         help='If rev1 is specified it will compare your working copy against '
                              'the revision (rev1) on the server. '
@@ -1123,6 +1126,20 @@ Please submit there instead, or use --nodevelproject to force direct submission.
         args = parseargs(args)
         pacs = findpacs(args)
 
+        if opts.change:
+            try:
+                rev = int(opts.change)
+                if rev > 0:
+                    rev1 = rev - 1
+                    rev2 = rev
+                elif rev < 0:
+                    rev1 = -rev
+                    rev2 = -rev - 1
+                else:
+                    return
+            except:
+                return
+        else:
             rev1, rev2 = parseRevisionOption(opts.revision)
         diff = ''
         for pac in pacs: