List existing contests as hint during import-contest

In 99% of the cases the user wants the last added contest but we choose to make
that choice explicit to prevent importing problems into the wrong contest.

Author: vmcj

misc-tools/import-contest.in

@@ -188,6 +188,11 @@ if os.path.exists('problems.yaml') or os.path.exists('problems.json') or os.path
         print('Importing problems.')
 
         if cid is None:
+            existing_contests = dj_utils.do_api_request('contests')
+            if existing_contests:
+                print("The DOMjudge server already has these contests:")
+            for c in existing_contests:
+                print(f"'{c['name']}' with cid: {c['id']}")
             cid = answer = input('Please specify the contest id: ')
 
         if not problems_imported: