`make install` on a module, I get `pgxs.mk:114: recipe for target 'install' failed` I'm trying to install a PostgreSQL module (pg-bignum). When I try make install, I get the following at the bottom of the log

/usr/bin/install: will not overwrite just-created '/usr/share/postgresql/9.5/extension/bignum--0.8.0.sql' with './/sql/bignum--0.8.0.sql'
/usr/lib/postgresql/9.5/lib/pgxs/src/makefiles/pgxs.mk:114: recipe for 
target 'install' failed
make: *** [install] Error 1


Currently using PostgreSQL-9.5 and Ubuntu.
That's a problem with the pg-bignum's Makefile. Filed upstream here.