Using Carp::confess to get stacktrace at one point

To try to diagnose CPANtesters failures from BingOS
# Please enter the commit message for your changes. Lines starting
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# On branch master
# Your branch is ahead of 'origin/master' by 1 commit.
#   (use "git push" to publish your local commits)
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# Changes to be committed:
#	modified:   lib/Devel/Git/MultiBisect.pm
#	modified:   t/010-run-test-files-combined.t
#
