Example failed koji task: https://koji.fedoraproject.org/koji/taskinfo?taskID=20474689

We recently started having ostree re-use the local mirror of content from the ISO image if it existed. We have it look in /ostree/repo and /run/install/repo in this line of code. At least for fedora 25 (according to the lorax template the real location was /run/install/repo/content/repo. However /run/install/repo/ is an actual directory on our media and has several things in there that anaconda uses. So /run/install/repo exists and is not an ostree repo.

This means that any ostree anaconda install that is initiated from a non-ostree install tree (like our atomic host qcows are in our pungi composes) will fail with this error:

 The following error occurred while installing.  This is a fatal error and      
 installation will be aborted.          

 Failed to pull from repository: g-io-error-quark: Opening objects/ directory:  
 openat: No such file or directory (1)

I'm thinking we should

1. fix the installer to look for the right location (PR here)
2. possibly make ostree not fail if a provided reference repo is bogus.

Thoughts?