make double_underscore_in_variable more robust

apkbuild-lint

@@ -230,7 +230,13 @@ pkgname_used_in_source() {
 double_underscore_in_variable() {
 	[ "$SKIP_DOUBLE_UNDERSCORE_IN_VARIABLE" ] && return 0
 	[ "$SKIP_AL30" ] && return 0
-	scan '(^|\t)(local ([A-Za-z_])?.*)?__.*(=)?' 'double underscore on variables are reserved' 'AL30' 'MC'
+	# Run this twice, once which will detect variables without the local keyword
+	# which requires matching the = sign at the end. The second time will match
+	# for variables declared with the local keyword which do not require the =
+	# sign
+	scan '(^|\t)?__[A-Za-z0-9_].*=' 'double underscore on variables are reserved' 'AL30' 'MC'
+	scan '(^|\t)local ([A-Za-z0-9_])?.*__[A-Za-z0-9_].*(=)?' 'double underscore on variables are reserved' 'AL30' 'MC'
+}
 }
 
 _run_apkbuild_leo() {