support request diffing relative to a former request

osc/commandline.py

@@ -2090,6 +2090,8 @@ def do_changedevelrequest(self, subcmd, opts, *args):
 
     @cmdln.option('-d', '--diff', action='store_true',
                   help='generate a diff')
+    @cmdln.option('-S', '--superseded-request', metavar='SUPERSEDED_REQUEST',
+                        help='Create the diff relative to a given former request')
     @cmdln.option('-u', '--unified', action='store_true',
                   help='output the diff in the unified diff format')
     @cmdln.option('--no-devel', action='store_true',
@@ -2512,8 +2514,15 @@ def do_request(self, subcmd, opts, *args):
                 diff = b''
                 try:
                     # works since OBS 2.1
-                    diff = request_diff(apiurl, reqid)
+                    diff = request_diff(apiurl, reqid, opts.superseded_request)
                 except HTTPError as e:
+                    if e.code == 404:
+                        # Any referenced object does not exist, eg. the superseded request
+                        root = ET.fromstring(e.read())
+                        summary = root.find('summary')
+                        print(summary.text, file=sys.stderr)
+                        raise oscerr.WrongOptions("Object does not exist")
+
                     # for OBS 2.0 and before
                     sr_actions = r.get_actions('submit')
                     if not r.get_actions('submit') and not r.get_actions('maintenance_incident') and not r.get_actions('maintenance_release'):

osc/core.py

@@ -4896,8 +4896,11 @@ def server_diff_noex(apiurl,
             return rdiff
 
 
-def request_diff(apiurl, reqid):
-    u = makeurl(apiurl, ['request', reqid], query={'cmd': 'diff'} )
+def request_diff(apiurl, reqid, superseded_reqid=None):
+    query = {'cmd': 'diff'}
+    if superseded_reqid:
+        query['diff_to_superseded'] = superseded_reqid
+    u = makeurl(apiurl, ['request', reqid], query)
 
     f = http_POST(u)
     return f.read()