Description of problem:

The latest version of pkconf broke usage of mock congiurations generated by fedpkg

Version-Release number of selected component (if applicable):
<mock-chroot> sh-5.0# rpm -q pkgconf
pkgconf-1.7.3-3.fc34.x86_64

How reproducible:
Determinisstic

Steps to Reproduce:
1. dnf isntall -y fedpkg mock
2. fedpkg clone --anonymous pkgconf
3. cd pkgconf
4. fedpkg mock-config > /etc/mock/default.cfg
5. fedpkg --shell
6. pkg-config

Actual results:
<mock-chroot> sh-5.0# pkg-config 
/usr/bin/pkg-config: line 7: /usr/bin/x86_64-koji-linux-gnu-pkg-config: No such file or directory

Expected results:
<mock-chroot> sh-5.0# pkg-config
Please specify at least one package name on the command line.

Additional info:

sh$ fedpkg mock-config | grep _host
config_opts['use_host_resolv'] = False
config_opts['macros']['%_host'] = 'x86_64-koji-linux-gnu'
config_opts['macros']['%_host_cpu'] = 'x86_64'