To be honest I know next to nothing about this codebase but apparently commit eab36c0001e22c0ee66246ae9a0b8018b2325c96 breaks building the tests of lgi (https://github.com/pavouk/lgi) with the following error. I'm not sure how this include is supposed to work:

/var/tmp/paludis/build/dev-lua-lgi-0.8.0-r3/work/LUA_ABIS/5.2/lgi-0.8.0 /var/tmp/paludis/build/dev-lua-lgi-0.8.0-r3/work
make -j5 LUA=/usr/bin/lua5.2 check
make -C lgi
make[1]: Entering directory '/var/tmp/paludis/build/dev-lua-lgi-0.8.0-r3/work/LUA_ABIS/5.2/lgi-0.8.0/lgi'
make[1]: Nothing to be done for 'all'.
make[1]: Leaving directory '/var/tmp/paludis/build/dev-lua-lgi-0.8.0-r3/work/LUA_ABIS/5.2/lgi-0.8.0/lgi'
make -C tests check
make[1]: Entering directory '/var/tmp/paludis/build/dev-lua-lgi-0.8.0-r3/work/LUA_ABIS/5.2/lgi-0.8.0/tests'
pkg-config --exists 'gio-2.0 cairo cairo-gobject gobject-introspection-1.0 gmodule-2.0 libffi >= 0.10.8' --print-errors
touch .depcheck
x86_64-pc-linux-gnu-gcc -fPIC   -I/usr/include/cairo -I/usr/include/pixman-1  -I/usr/include/freetype2 -I/usr/include/harfbuzz -I/usr/include/libdrm -I/usr/include/libpng16 -I/usr/include/gobject-introspection-1.0 -pthread -I/usr/include/glib-2.0 -I/usr/lib64/glib-2.0/include -I/usr/lib64/libffi-3.1/include   -march=native -pipe -O2 -floop-block -floop-interchange -floop-strip-mine -c -o regress.o /usr/share/gobject-introspection-1.0/tests/regress.c
/usr/share/gobject-introspection-1.0/tests/regress.c:2:20: fatal error: config.h: No such file or directory
 #include "config.h"
                    ^
compilation terminated.
Makefile:67: recipe for target 'regress.o' failed
make[1]: Leaving directory '/var/tmp/paludis/build/dev-lua-lgi-0.8.0-r3/work/LUA_ABIS/5.2/lgi-0.8.0/tests'
make[1]: *** [regress.o] Error 1
Makefile:31: recipe for target 'check' failed
make: *** [check] Error 2