Python: Replace '.prefix'/'.suffix' with '.matches'.

python/ql/lib/semmle/python/templates/PyxlTags.qll

@@ -29,7 +29,7 @@ private predicate pyxl_tag(Call c, string name) {
 }
 
 class PyxlHtmlTag extends PyxlTag {
-  PyxlHtmlTag() { this.getPyxlTagName().prefix(2) = "x_" }
+  PyxlHtmlTag() { this.getPyxlTagName().matches("x\\_%") }
 
   string getTagName() { result = this.getPyxlTagName().suffix(2) }
 

python/ql/lib/semmle/python/web/Http.qll

@@ -33,7 +33,7 @@ class WsgiEnvironment extends TaintKind {
       (
         text = "QUERY_STRING" or
         text = "PATH_INFO" or
-        text.prefix(5) = "HTTP_"
+        text.matches("HTTP\\_%")
       )
     )
   }