print preciser error messages when retrieving failed

Signed-off-by: Sebastian Schüpbach <sebastian.schuepbach@unibas.ch>
3 jobs for master in 7 minutes and 59 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
passed #57636
mbr
test-sbt

00:04:02

 
  Build
passed #57637
mbr
assembly-sbt

00:01:58

 
  Publish
passed #57638
mbr
build-latest-image

00:01:59