Cygwin - t/env.t not running last 3 tests

[rwhitworth]

When using Cygwin the t/env.t test fails because only the first 10 tests run. The final 3 tests do not run at all. Changing the number of tests from 13 to 10 causes the results of make test or prove -b t/*.t to succeed.

I don't see any reason why perl would skip the last three tests. CPAN Testers, here, shows this module often has trouble in Cygwin. Any ideas as to why this happens or how I can help resolve the issue?