A person subject to this Act who commits an offence of murder against a person not subject to military, naval or air force law, or of culpable homicide not amounting to murder against such a person or of rape in relation to such a person, shall not be deemed to be guilty of an offence against this Act and shall not be tried by a court-martial, unless he commits any of the said offences—
(a) while on active service, or
(b) at any place outside India, or
(c) at a frontier post specified by the Central Government by notification in this behalf. * * * * *