Fals only 10 tests on my system (Talos II, 32bit chroot).

[...]
[  FAILED  ] 10 tests, listed below:
[  FAILED  ] BCacheTests.cleaned_on_demand
[  FAILED  ] IOEngineTests.empty_test
[  FAILED  ] IOEngineTests.open_and_close
[  FAILED  ] IOEngineTests.you_can_read_a_read_only_handle
[  FAILED  ] IOEngineTests.you_cannot_write_to_a_read_only_handle
[  FAILED  ] IOEngineTests.you_can_write_to_a_read_write_handle
[  FAILED  ] IOEngineTests.final_block_read_succeeds
[  FAILED  ] IOEngineTests.out_of_bounds_read_fails
[  FAILED  ] IOEngineTests.out_of_bounds_write_succeeds
[  FAILED  ] IOEngineTests.succeed_with_timeout

10 FAILED TESTS
make: *** [unit-tests/Makefile:98: unit-test] Error 1
 * ERROR: sys-block/thin-provisioning-tools-0.9.0::gentoo failed (test phase):
 *   emake failed