Merge pull request #10805 from ipython/auto-backport-of-pr-10797

Backport PR  #10797 on branch 5.x

IPython/core/completer.py

@@ -1093,6 +1093,12 b' class IPCompleter(Completer):'
                     return [cast_unicode_py2(r) for r in res if r.lower().startswith(text_low)]
             except TryNext:
                 pass
+            except KeyboardInterrupt:
+                """
+                If custom completer take too long,
+                let keyboard interrupt abort and return nothing.
+                """
+                break
 
         return None