https://launchpadlibrarian.net/418304406/buildlog_ubuntu-cosmic-amd64.nss_2%3A3.36.1-1ubuntu1_BUILDING.txt.gz
make[2]: Entering directory '/<<PKGBUILDDIR>>/nss/coreconf/nsinstall'
x86_64-linux-gnu-gcc -o OBJS/nsinstall.o -c -g -fPIC -pipe -ffunction-sections -fdata-sections -DHAVE_STRERROR -DLINUX -Dlinux -Wall -Werror -DXP_UNIX -DDEBUG -UNDEBUG -DDEBUG_buildd -D_REENTRANT -DNSS_NO_INIT_SUPPORT -DUSE_UTIL_DIRECTLY -DNO_NSPR_10_SUPPORT -DSSL_DISABLE_DEPRECATED_CIPHER_SUITE_NAMES -I/<<PKGBUILDDIR>>/dist/include -I/<<PKGBUILDDIR>>/dist/public/coreconf -I/<<PKGBUILDDIR>>/dist/private/coreconf nsinstall.c
x86_64-linux-gnu-gcc -o OBJS/pathsub.o -c -g -fPIC -pipe -ffunction-sections -fdata-sections -DHAVE_STRERROR -DLINUX -Dlinux -Wall -Werror -DXP_UNIX -DDEBUG -UNDEBUG -DDEBUG_buildd -D_REENTRANT -DNSS_NO_INIT_SUPPORT -DUSE_UTIL_DIRECTLY -DNO_NSPR_10_SUPPORT -DSSL_DISABLE_DEPRECATED_CIPHER_SUITE_NAMES -I/<<PKGBUILDDIR>>/dist/include -I/<<PKGBUILDDIR>>/dist/public/coreconf -I/<<PKGBUILDDIR>>/dist/private/coreconf pathsub.c
pathsub.c: In function ‘reversepath’:
pathsub.c:215:6: error: ‘strncpy’ output truncated before terminating nul copying 3 bytes from a string of the same length [-Werror=stringop-truncation]
strncpy(cp, "../", 3);
^~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
make[2]: *** [../../coreconf/rules.mk:393: OBJS/pathsub.o] Error 1
make[2]: Leaving directory '/<<PKGBUILDDIR>>/nss/coreconf/nsinstall'
make[1]: *** [debian/rules:106: override_dh_auto_build] Error 2
make[1]: Leaving directory '/<<PKGBUILDDIR>>'
make: *** [debian/rules:201: build] Error 2
fixed in the -updates pocket