That leads to calling load_repo_name() again

I tested the case you are talking about. Let's have for example random repository that doesn't contain Dockerfile:
https://src.fedoraproject.org/container/container-engine
fedpkg verrel behaves well here.

The issue with endless recursion could potentially appear when load_repo_name() doesn't find "push_url".
Did you find any specific repo that you could observe it?

However, I am more open to change these messages. Additional information in messages is not a major loss.

Apologies, the pull request description is too terse.
A fresh Fedora contributor actually hit the endless recursion when they were trying to follow the Packaging Tutorial from the Package Maintainer Docs.
Unfortunately, due to other, unrelated issues, threading in the devel discussion broke,
so it is very difficult to find the ensuing discussion from the mailing list archives.
Anyhow, the initial message is here:
fedpkg: Failed to get repository name from Git url or pushurl

The recursion happened because two conditions were fulfilled:

1. Specfile was corrupted and not valid UTF-8, leading to an exception when load_nameverrel() is called.
2. fedpkg was called outside of Git repository, leading to an alternate code path inside load_repo_name() that calls load_nameverrel() before anything else has a chance.

So if you corrupt a specfile with a hex editor,
then try to do something to it with fedpkg without a Git repository,
you will reproduce #657.

Thanks for the extended explanation. I didn't look at #657, my bad. Otherwise, I would have had enough information.
But as I indicated in the post above, I will rather lose some details in the message than risk an endless loop (although it is rare).

Apologies, the pull request description is too terse.

Btw, I generally think you are the most descriptive contributor :-).

Commit 7c61ddf0 fixes this pull-request