[ruby/did_you_mean] Avoid division for small length2

https://github.com/ruby/did_you_mean/commit/cb518e251a

lib/did_you_mean/jaro_winkler.rb

@@ -8,8 +8,7 @@ module DidYouMean
 
       m          = 0.0
       t          = 0.0
-      range      = length2 / 2 - 1
-      range      = 0 if range < 0
+      range      = length2 > 3 ? length2 / 2 - 1 : 0
       flags1     = 0
       flags2     = 0