distro_info: use yum for CentOS/7

bin/distro_info

@@ -48,7 +48,8 @@ override_distrib()
 {
 	[ -n "$1" ] || return
 	VENDOR_ID=''
-	DISTRIB_ID="$1"
+	DISTRIB_ID="$(echo "$1" | sed -e 's|/.*||')"
+	DISTRIB_RELEASE="$(echo "$1" | sed -e 's|.*/||')"
 }
 
 # Translate DISTRIB_ID to vendor name (like %_vendor does), uses VENDOR_ID by default
@@ -135,6 +136,7 @@ case $DISTRIB_ID in
 	Fedora|LinuxXP|ASPLinux|CentOS|RHEL|Scientific|GosLinux|Amzn|RedOS)
 		CMD="dnf-rpm"
 		which dnf 2>/dev/null >/dev/null || CMD=yum-rpm
+		[ "$DISTRIB_ID/$DISTRIB_RELEASE" = "CentOS/7" ] && CMD=yum-rpm
 		;;
 	Slackware)
 		CMD="slackpkg"