If a command fails to execute but does not print anything to standard error,...

If a command fails to execute but does not print anything to standard error, try and include the first line of standard output in the message we include in the diff. This was motivated by readelf(1) returning its error messages on stdout. (Closes: #931963, #59)
4 jobs for master in 16 minutes and 15 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Test
passed #221161
allowed to fail
stable-bpo

00:15:33

88.0%
passed #221160
testing

00:15:55

88.0%
failed #221162
allowed to fail
ubuntu-devel

00:09:31

passed #221159
unstable

00:16:15

88.0%
 
Name Stage Failure
failed
ubuntu-devel Test
done.
done.
Processing triggers for libgdk-pixbuf2.0-0:amd64 (2.38.1+dfsg-1) ...
Errors were encountered while processing:
linux-firmware
linux-image-generic
E: Sub-process /usr/bin/dpkg returned an error code (1)
E: Failed to process build dependencies
ERROR: Job failed: exit code 1