
After disconnecting hair on an object, if you then hide the particle system, and try connecting the hair again, the operator is cancelled due to `remap_hair_emitter` returning `false` because `target_psmd->mesh_final` is NULL, but `connect_hair` will still strip the `PSYS_GLOBAL_HAIR` flag, which will cause the hair in the hidden particle system to be positioned incorrectly. The correct behavior is to strip the flag only if `remap_hair_emitter` succeeds. Differential Revision: https://developer.blender.org/D13703