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The functions moveins(), copyins(), moveouts(), copyouts() are required to preserve the invariant that there are no duplicate arcs in the regex's NFA. Spencer's original implementation of them was O(N^2) since it checked separately for a match to each source arc. In commit 579840ca0 I improved that by adding sort/merge logic to be used if more than a few arcs are to be moved/copied. However, I now realize that that missed a bet. At many call sites, the target state is newly made and cannot have any existing in-arcs (respectively out-arcs) that could be duplicates. So spending any cycles at all on checking for duplicates is wasted effort; in these cases we can just blindly move/copy all the source arcs. Add code paths to do that. It turns out that for copyins()/copyouts(), *all* the call sites have this property, making all the "improved" logic in them flat out unreachable. Perhaps we'll need the full capability again someday, so I just #ifdef'd those paths out rather than removing them entirely. In passing, add a few test cases to improve code coverage in this area as well as in regc_locale.c/regc_pg_locale.c. Discussion: https://postgr.es/m/810272.1629064063@sss.pgh.pa.us