Merge branch 'ab/checkout-branch-info-leakfix'

We added an unrelated sanity checking that leads to a BUG() while plugging a leak, which triggered in a repository with symrefs in the local branch namespace that point at a ref outside. Partially revert the change to avoid triggering the BUG(). * ab/checkout-branch-info-leakfix: checkout: avoid BUG() when hitting a broken repository