Description of problem:
I'm trying to update the python-tdlib package for the new boost package.  Everything is fine until %configure is invoked.

...
+ export LDFLAGS
+ LT_SYS_LIBRARY_PATH=/usr/lib64:
+ export LT_SYS_LIBRARY_PATH
+ CC=gcc
+ export CC
+ CXX=g++
+ export CXX
/var/tmp/rpm-tmp.u359Mv: line 42: syntax error near unexpected token `;'

And /var/tmp/rpm-tmp.u359Mv shows:
  LT_SYS_LIBRARY_PATH="${LT_SYS_LIBRARY_PATH:-/usr/lib64:}" ; export LT_SYS_LIBR
ARY_PATH ; 
  CC=gcc; export CC ; 
  CXX=g++; export CXX ; 
  ; 

^^^^ That is line 42.

In /usr/lib/rpm/redhat/macros, I see this on lines 180 and 181:

%configure \
  %{set_build_flags}; \
                    ^
That semicolon -----| is the one causing the problem.

Version-Release number of selected component (if applicable):
redhat-rpm-config-159-1.fc33.noarch

How reproducible:
Always.

Steps to Reproduce:
1. fedpkg cone python-tdlib
2. cd python-tdlib
3. fedpkg srpm
4. mock -r fedora-rawhide-x86_64 --enablerepo=local --rebuild python-tdlib-*.src.rpm

Actual results:
Failure while executing %configure.

Expected results:
Success while executing %configure.

Additional info: