define approx_original_sources :=
${SOURCES}
endef
export approx_original_sources

ifdef approx
  BOOTSTRAP := ${approx}
  define SOURCES =
  deb ${approx} ${release} main
  endef
else ifdef raspi
  BOOTSTRAP := http://localhost/raspbian
  define SOURCES :=
  deb http://localhost/raspbian ${release} main non-free firmware rpi
  deb http://localhost/rpidebian ${release} main
  endef
else
  BOOTSTRAP := http://localhost/debian
  define SOURCES :=
  deb http://localhost/debian ${release} main
  endef
endif

.PHONY: _approx_restore_sources
_config: _approx_restore_sources
_approx_restore_sources: ${CFGROOT}
	printf '%s\n' "$${approx_original_sources}" >"$${CFGROOT}/etc/apt/sources.list"