It would be nice if you could change the goal of merging the pull request. It would also be nice if you could collaborate on a tensile request before accepting it to fix minor issues. AFIAK Github does not allow any of these things. You have a choice ...
- Make a merge manually and thank the author in a comment on PR explaining why he did not merge directly into master.
- Ask the author to resubmit the transfer request to the function branches.
- Ask the author to make corrections.
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