testsuite: fix tests/basic/patmatch_incoherence.ml
testsuite: fix tests/basic/patmatch_incoherence.ml

Make this brittle test more robust by being less precise.

gerdstolpmann/ocaml,gerdstolpmann/ocaml,gerdstolpmann/ocaml,gerdstolpmann/ocaml,gerdstolpmann/ocaml