reconstruct_identifier: fix off-by-one (fixes #624 )
reconstruct_identifier: fix off-by-one (fixes #624 )

ocaml/merlin,the-lambda-church/merlin,rgrinberg/merlin,ocaml/merlin,rgrinberg/merlin,the-lambda-church/merlin,rgrinberg/merlin,rgrinberg/merlin,the-lambda-church/merlin,dra27/merlin,ocaml/merlin,dra27/merlin,ocaml/merlin,dra27/merlin,dra27/merlin