Check fails (exit status 137)

[elgohr]

From time to time the resource returns
"resource script '/opt/resource/check []' failed: exit status 137".

The resource is configured as

• name: firefox-sources
  type: debian-sources
  check_every: 4h
  source:
  arch: i386
  sources:
  • deb http://ppa.launchpad.net/mozillateam/ppa/ubuntu xenial main