Derivation BPHY: Fix undef behaviour as warned by cppcheck

Fix warning as found in:

ATLASSQ-377 ATLASSQ-376 ATLASSQ-375 ATLASSQ-374 ATLASSQ-373

While this was technically undefined behaviour I think it was working as intended anyway. Still it should be fixed.

added bugfix label

This merge request affects 1 package:

• PhysicsAnalysis/DerivationFramework/DerivationFrameworkBPhys

This merge request affects 1 file:

• PhysicsAnalysis/DerivationFramework/DerivationFrameworkBPhys/src/CascadeTools.cxx

Adding @wwalko ,@abarton as watchers

added Derivation master review-pending-level-1 labels

CI Result SUCCESS (hash a2a5e3f4)

	Athena	AthSimulation	AthGeneration	AnalysisBase	AthAnalysis
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
AthAnalysis: number of compilation errors 0, warnings 0
For experts only: Jenkins output [CI-MERGE-REQUEST-CC7 27985]

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

merged

mentioned in commit 0e3c68b3

added sweep:ignore label