Protect against negative elements on the diagonal of covariance matrices

In rare occasions, the track fit may result in parameters with unphysical covariance matrices. This can occur if the inputs to the fit are themselves unphysical: e.g., ID tracks with pT of hundreds of TeV. This fix adds a protection against such tracks, to avoid crashes down the line. (It was prompted by a crash of exactly this kind in one of the MooPerformance RTT tests.)

WARNING: big files (>100K) are found in the changeset

188K in file Reconstruction/MuonIdentification/MuidTrackBuilder/src/CombinedMuonTrackBuilder.cxx

This merge request affects 1 package:

• Reconstruction/MuonIdentification/MuidTrackBuilder

Adding @rosati ,@wleight as watchers

added Reconstruction master review-pending-level-1 labels

CI Result SUCCESS

	Athena	AthSimulation
externals
cmake
make
required tests
optional tests

Full details available at NICOS MR-26401-2019-09-06-22-49
Athena: number of compilation errors 0, warnings 0
AthSimulation: number of compilation errors 0, warnings 0
For experts only: Jenkins output [CI-MERGE-REQUEST-CC7 3052]

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

merged

mentioned in commit 8bf75f61

added sweep:ignore label