Can I rebuild a src rpm in F27 beta?

edit

Thanks davidva for your answer. I haven't used mock before so I'll try that. However when I went to install mock with dnf it wanted to downgrade systemd, systemd-libs, systemd-pam & systemd-udev. So I didn't go ahead with the install. And now seem to be stuck again.

Do you have enable "update-testing" if not enable it ( /etc/yum.repos.d/fedora-updates-testing.repo ). I am using mock without problem en Fedora 27... Now a simple....

su

dnf -y distro-sync

OK I'll try that - thanks. Maybe this is the cause of all my problems.

After enabling 'updates-testing' I keep getting "Status code 404" and "No more mirrors to try - All mirrors were already tried without success" on a dnf upgrade. Also with a simple "dnf install mock" I get the same response - error downloading packages and "Cannot download Packages". All mirrors were already tried without success.

I guess I just need to wait for the mirrors to sync with 'updates-testing'.

I had to add "&country=us" to the end of the metalink lines in the fedora-updates-testing.repo file in /etc/yum.repos.d/ to force the use of a U.S. mirror which must be more up-to-date because I can now do a system upgrade and install mock.