Return fast in an easily detectable and common use case

lib/brakeman/checks/check_link_to_href.rb

@@ -35,6 +35,7 @@ class Brakeman::CheckLinkToHref < Brakeman::CheckLinkTo
     call = result[:call] = result[:call].dup
     @matched = false
     url_arg = process call[3][2]
+    return if sexp?(url_arg) && url_arg.node_type == :string_interp && !url_arg[1].chomp.empty?
     type, match = has_immediate_user_input? url_arg
 
     if type