Devel::Confess before 0.007005 would hand us a warning message without a newline, causing Test::Warnings itself to be reported as the origin of the warning

to reproduce:
perl -wle'use Test::Warnings ":no_end_test"; use Devel::Confess; warn "foo"'
(resolved in RT#100951)
Test-Warnings-0.017

          - handle other warning handlers passing us partial warning messages
            by re-adding the source file and line number