Add helpful message to debugger log
Add helpful message to debugger log

Change-Id: I5fd7c09d1ad06311d171c7c236c4307c213068cc
Reviewed-on: https://skia-review.googlesource.com/c/buildbot/+/512723
Reviewed-by: Kevin Lubick <7cdab2cfab351f23814786ba39716e90eed69047@google.com>
Commit-Queue: Nathaniel Nifong <1ce561679465ea4956c6210637580cd7ba456816@google.com>

google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot