RPM erroneously executes macros in comments.

For instance, the following in %build

%build
# The configure script uses FCFLAGS instead of FFLAGS declared by the %configure macro.
export FCFLAGS="%{optflags} -ffree-form -ffree-line-length-none -I%{_fmoddir}"
%configure

will cause RPM to run %configure on the first line, before the FCFLAGS variable has been declared. It *really* should not do that.