pygobject is currently breaking the unstable gnome sdk build, as can be seen here:
http://sdkbuilder1.gnome.org/logs/build-2017-01-19-082820/build-gnome-sdk-images-master-x86_64.txt

Note, this is a large file, so you might want to be careful viewing it in the browser. Anyway, it ends:

libtool: compile:  gcc -DHAVE_CONFIG_H -I. -I.. -I../gi -I/usr/include/python3.4m -I/usr/include/python3.4m -pthread -I/usr/include/glib-2.0 -I/usr/lib/glib-2.0/include -O2 -g -Wall -Werror=unused-variable -fno-strict-aliasing -Werror=declaration-after-statement -Wall -Wstrict-prototypes -Wnested-externs -Werror=missing-prototypes -Werror=implicit-function-declaration -Werror=pointer-arith -Werror=init-self -Werror=format=2 -Werror=missing-include-dirs -Werror=return-type -MT testhelper_la-test-unknown.lo -MD -MP -MF .deps/testhelper_la-test-unknown.Tpo -c test-unknown.c  -fPIC -DPIC -o .libs/testhelper_la-test-unknown.o
libtool: compile:  gcc -DHAVE_CONFIG_H -I. -I.. -pthread -I/usr/include/glib-2.0 -I/usr/lib/glib-2.0/include -I/usr/include/cairo -I/usr/include/pixman-1 -I/usr/include/freetype2 -I/usr/include/libpng16 -I/usr/include/freetype2 -I/usr/include/harfbuzz -I/usr/include/libpng16 -I/usr/include/glib-2.0 -I/usr/lib/glib-2.0/include -O2 -g -Wall -Werror=unused-variable -fno-strict-aliasing -Werror=declaration-after-statement -Wall -Wstrict-prototypes -Wnested-externs -Werror=missing-prototypes -Werror=implicit-function-declaration -Werror=pointer-arith -Werror=init-self -Werror=format=2 -Werror=missing-include-dirs -Werror=return-type -MT libregress_la-regress.lo -MD -MP -MF .deps/libregress_la-regress.Tpo -c /usr/share/gobject-introspection-1.0/tests/regress.c  -fPIC -DPIC -o .libs/libregress_la-regress.o
mv -f .deps/testhelper_la-test-unknown.Tpo .deps/testhelper_la-test-unknown.Plo
mv -f .deps/libgimarshallingtests_la-gimarshallingtestsextra.Tpo .deps/libgimarshallingtests_la-gimarshallingtestsextra.Plo
mv -f .deps/libgimarshallingtests_la-gimarshallingtests.Tpo .deps/libgimarshallingtests_la-gimarshallingtests.Plo
/bin/sh ../libtool  --tag=CC   --mode=link gcc  -O2 -g -Wall -Werror=unused-variable -fno-strict-aliasing -Werror=declaration-after-statement  -Wall -Wstrict-prototypes -Wnested-externs -Werror=missing-prototypes -Werror=implicit-function-declaration -Werror=pointer-arith -Werror=init-self -Werror=format=2 -Werror=missing-include-dirs -Werror=return-type    -L/app/lib   -o libgimarshallingtests.la -rpath /usr/lib/python3.4/site-packages/pygobject -module -avoid-version -lgobject-2.0 -lgthread-2.0 -pthread -lglib-2.0 -no-undefined libgimarshallingtests_la-gimarshallingtestsextra.lo libgimarshallingtests_la-gimarshallingtests.lo  
mv -f .deps/testhelper_la-test-floating.Tpo .deps/testhelper_la-test-floating.Plo
mv -f .deps/testhelper_la-testhelpermodule.Tpo .deps/testhelper_la-testhelpermodule.Plo
mv -f .deps/testhelper_la-test-thread.Tpo .deps/testhelper_la-test-thread.Plo
/bin/sh ../libtool  --tag=CC   --mode=link gcc  -O2 -g -Wall -Werror=unused-variable -fno-strict-aliasing -Werror=declaration-after-statement  -Wall -Wstrict-prototypes -Wnested-externs -Werror=missing-prototypes -Werror=implicit-function-declaration -Werror=pointer-arith -Werror=init-self -Werror=format=2 -Werror=missing-include-dirs -Werror=return-type    -L/app/lib   -o testhelper.la -rpath /usr/lib/python3.4/site-packages/pygobject -module -avoid-version -no-undefined  testhelper_la-testhelpermodule.lo testhelper_la-test-floating.lo testhelper_la-test-thread.lo testhelper_la-test-unknown.lo -lgobject-2.0 -lgthread-2.0 -pthread -lglib-2.0 
libtool: link: gcc -shared  -fPIC -DPIC  .libs/libgimarshallingtests_la-gimarshallingtestsextra.o .libs/libgimarshallingtests_la-gimarshallingtests.o   -L/app/lib /usr/lib/libgobject-2.0.so -L/usr/lib -L/usr/lib/../lib -lffi /usr/lib/libgthread-2.0.so /usr/lib/libglib-2.0.so -lpcre -lpthread  -O2 -g -pthread   -pthread -Wl,-soname -Wl,libgimarshallingtests.so -o .libs/libgimarshallingtests.so
libtool: link: gcc -shared  -fPIC -DPIC  .libs/testhelper_la-testhelpermodule.o .libs/testhelper_la-test-floating.o .libs/testhelper_la-test-thread.o .libs/testhelper_la-test-unknown.o   -L/app/lib /usr/lib/libgobject-2.0.so -L/usr/lib -L/usr/lib/../lib -lffi /usr/lib/libgthread-2.0.so /usr/lib/libglib-2.0.so -lpcre -lpthread  -O2 -g -pthread   -pthread -Wl,-soname -Wl,testhelper.so -o .libs/testhelper.so
libtool: link: ( cd ".libs" && rm -f "libgimarshallingtests.la" && ln -s "../libgimarshallingtests.la" "libgimarshallingtests.la" )
test -L libgimarshallingtests.so || ln -s .libs/libgimarshallingtests.so libgimarshallingtests.so
libtool: link: ( cd ".libs" && rm -f "testhelper.la" && ln -s "../testhelper.la" "testhelper.la" )
test -L testhelper.so || ln -s .libs/testhelper.so testhelper.so
/usr/share/gobject-introspection-1.0/tests/regress.c:3456:804: error: no previous prototype for ‘_regress_test_fundamental_hidden_sub_object_get_type’ [-Werror=missing-prototypes]
cc1: some warnings being treated as errors
Makefile:559: recipe for target 'libregress_la-regress.lo' failed
make[2]: *** [libregress_la-regress.lo] Error 1
make[2]: Leaving directory '/run/build-runtime/pygobject/tests'
Makefile:675: recipe for target 'all-recursive' failed
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory '/run/build-runtime/pygobject'
Makefile:498: recipe for target 'all' failed
make: *** [all] Error 2
Error: module pygobject: Child process exited with code 2
make: *** [all] Error 1