makechrootpkg: load makepkg.conf variables correctly

Since makepkg.conf is a bash-compatible configuration file, it must be
sourced.

Signed-off-by: Eli Schwartz <eschwartz@archlinux.org>
Signed-off-by: Levente Polyak <anthraxx@archlinux.org>

makechrootpkg.in

@@ -69,7 +69,7 @@ load_vars() {
 	[[ -f $makepkg_conf ]] || return 1
 
 	for var in {SRC,SRCPKG,PKG,LOG}DEST MAKEFLAGS PACKAGER; do
-		[[ -z ${!var:-} ]] && eval "$(grep -a "^${var}=" "$makepkg_conf")"
+		[[ -z ${!var:-} ]] && eval "$(source "$makepkg_conf"; printf "%s='%s'" "$var" "${!var}")"
 	done
 
 	return 0