manyabot's sed should only look at prefixes of lines

[ChimeraCoder]

Note the following exchange, in which /us/app inside a URL triggers manyabot's sed functionality erroneously.

              │15:22:48 +chimeracoder | josePhoenix: apparently this is one: ?                     
              │15:22:49       +exchgr | but why                                                    │
              │15:22:53           --> | jetfault (~jetfault@nat/yahoo/x-mlckxsxnascitqrn) has      
              │                       | joined #hackny                                             │
              │15:22:53 +chimeracoder | https://itunes.apple.com/us/app/minikeepass-secure-passwor │
              │                       | d/id451661808?mt=8                                         │
              │15:22:54      manyabot | chimeracoder really meant to say: josePhoenix:             
              │                       | minikeepass-secure-passwordarently this is one: ?          │