$ gcc -O2 -Wall -D_GNU_SOURCE posix/tst-nice.c -o tst-nice $ nice -n19 ./tst-nice FAIL: retval (19) of nice(10) != 29 As a consequence, eglibc FTBFS when built with such a high niceness.
tag 608332 + wontfix thanks eglibc provides low level functions more or less corresponding to kernel syscalls. The associated testsuite tests these low level functions and thus require that the syscalls behave as expected. If you change the environment to the point that some syscalls behave differently than expected, it doesn't make sense to run the testsuite. It is possible to disable it defining DEB_BUILD_OPTIONS="nocheck". I am therefore tagging this bug as wontfix.