I was missing the -i flag to sed.
@ -305,7 +305,7 @@ sed -i -e 's!\./!!g' \
%ifnarch x86_64
# most arches run out of memory with full debuginfo, so use -g1 on non-x86_64
sed -e 's/=-g$/=-g1/g' src/core/gyp_run.pro
sed -i -e 's/=-g$/=-g1/g' src/core/gyp_run.pro
%endif
%build