Fix an issue that multi muon trigger(>= 3 muons) chains don't work, ATR-20136

I would like to merge these changes into master.
This fixes an issue reported on ATR-20136. I confirmed that these changes don't have any effect to other chains by test_trigUpgr_full_menu_mc_build.

This merge request affects 1 package:

• Trigger/TrigHypothesis/TrigMuonHypoMT

added Trigger master review-pending-level-1 labels

CI Result SUCCESS

	Athena	AthSimulation
externals
cmake
make
required tests
optional tests

Full details available at NICOS MR-25369-2019-08-05-19-00
Athena: number of compilation errors 0, warnings 1
AthSimulation: number of compilation errors 0, warnings 0
For experts only: Jenkins output [CI-MERGE-REQUEST-CC7 1813]

changed the description

Changes look ok, build warnings seem unrelated to this MR. Approving. Catrin (L1)

added review-approved label and removed review-pending-level-1 label

merged

mentioned in commit 37e78cd5

added sweep:ignore label