Remove source from fetch error message
Remove source from fetch error message

The source is already included in the error, so it is redundant, eg:

pprof http://nowhere.nothere
Currently produces:
http://nowhere.nothere: http fetch http://nowhere.nothere: Get http://nowhere.nothere: dial tcp: lookup nowhere.nothere: no such host

With this commit:
http://nowhere.nothere: http fetch: Get http://nowhere.nothere: dial tcp: lookup nowhere.nothere: no such host

rauls5382/pprof,google/pprof,rauls5382/pprof,google/pprof,google/pprof,google/pprof