Bug#1004043: git-annex: test --pattern can segfault

[Benjamin Barenblat]

Package: git-annex
Version: 8.20210223-2
Severity: normal

Passing certain patterns to `git annex test -p` causes a segfault:

    $ git annex test -p 'Tests.Unit Tests v8 locked.move'
    error: git-annex died of signal 11

Other patterns work fine:

    $ git annex test -p Tests.QuickCheck.prop_VectorClock_sane
    Tests
      QuickCheck
        prop_VectorClock_sane: OK
          +++ OK, passed 1 test.

    All 1 tests passed (0.00s)

Running all the tests (i.e., `git annex test` without `-p`) also works
fine, and all the tests pass.