The forge bridge wrote no merged message for such a merge, so taken.<repo> never moved
and the view held 'the indexer has not yet taken in <head>' (hq #490-#492). The bridge
now writes it with no trees; the indexer drops every module of the repository on it,
after the same order check as any merged message. The view needed no change: with the
taken key moving it reaches the merge, which its new row proves.
Needs mesh-sdk fix/1126-no-module-reach (a merged message may carry no trees).