Unable to build due to failing nptl tests

I am attempting to build the glibc packages from source. The commands used to fetch the source package and build it are as follows:

apt-get build-dep glibc
apt-get source glibc
cd glibc-2.27/
debuild -us -uc 1>../stdout.txt 2>../stderr.txt

I initially tried to build the package on my Ubuntu 18.04 workstation, which had the gdb and python-pexpect packages installed and the following tests failed:

FAIL: nptl/test-condattr-printers
FAIL: nptl/test-cond-printers
FAIL: nptl/test-mutexattr-printers
FAIL: nptl/test-mutex-printers
FAIL: nptl/test-rwlockattr-printers
FAIL: nptl/test-rwlock-printers

Some research showed that these tests require the gdb and python-pexpect (or python3-pexpect) packages to be installed in order to run. Since these packages are not included in the list of build dependencies, I created a virtual machine with a minimal Ubuntu 18.04 install and ran the same build commands. This time around, those tests were all marked as "UNSUPPORTED":

UNSUPPORTED: nptl/test-cond-printers
UNSUPPORTED: nptl/test-condattr-printers
UNSUPPORTED: nptl/test-mutex-printers
UNSUPPORTED: nptl/test-mutexattr-printers
UNSUPPORTED: nptl/test-rwlock-printers
UNSUPPORTED: nptl/test-rwlockattr-printers

Interestingly, there were also a few tests that were marked as "UNSUPPORTED" in both cases, which seems to be due to the hardware I'm building on and not any missing package:

UNSUPPORTED: elf/tst-audit10
UNSUPPORTED: elf/tst-avx512
UNSUPPORTED: math/test-double-libmvec-alias-avx512
UNSUPPORTED: math/test-double-libmvec-alias-avx512-main
UNSUPPORTED: math/test-double-libmvec-sincos-avx512
UNSUPPORTED: math/test-float-libmvec-alias-avx512
UNSUPPORTED: math/test-float-libmvec-alias-avx512-main
UNSUPPORTED: math/test-float-libmvec-sincosf-avx512
UNSUPPORTED: misc/tst-pkey

The question here is whether or not this behavior is expected. If this package is built upstream in a chroot environment with something like pbuilder, I would imagine that the gdb and python-pexpect (or python3-pexpect) packages would not be installed in this environment and that the tests would be skipped. Are these tests being skipped upstream, or does their failure on my workstation indicate a deeper issue?