HLTUtils: Fix for python 2 compatibility.

Make sure getoutput() is in the subprocess module. We still have a python 2 build, so we want thigs to work with both py2 and py3.

This merge request affects 1 package:

• HLT/HLTUtils

Adding @bernius ,@wiedenma ,@rbielski ,@fwinkl as watchers

added Trigger master review-pending-level-1 labels

CI Result SUCCESS (hash f558b763)

	Athena	AthSimulation	AthGeneration	AnalysisBase
externals
cmake
make
required tests
optional tests

Full details available on this CI monitor view
Athena: number of compilation errors 0, warnings 0
AthSimulation: number of compilation errors 0, warnings 0
AthGeneration: number of compilation errors 0, warnings 0
AnalysisBase: number of compilation errors 0, warnings 0
For experts only: Jenkins output [CI-MERGE-REQUEST-CC7 17912]

merged

mentioned in commit 7542e2fd

added sweep:ignore label