If I correctly understand it, there are 2 use cases:
- transplanting from another repo
- transplanting from another branch (of the current repo)
In case 1, why am I seeing the branch selector? I can click the "transplant from a branch" and then I see the branches in the current repo...
In case 2, why am I seeing the repo URL even if disabled?
This whole thing misleading. Misleading labels, misleading controls, misleading interaction (enabling/disabling, clearing content of the URL input box, branch selector showing the branches of the current repo, not those of the repo at the URL, etc.)
My suggestion: to clear this up, add a new step before the current first one where you can select between the 2 main use cases with 2 radiobuttons. This will also significantly simplify the currently first screen.