Fix primary issue in #300 context path is always the context path

The context path does not change to "" just because the current request
matches a context root mapping.

spec/src/main/asciidoc/servlet-spec-body.adoc

@@ -6097,7 +6097,7 @@ is used as an extension mapping.
 * The empty string (`+""+`) is a special URL pattern
 that exactly maps to the application's context root, i.e., requests of
 the form `http://host:port/<context-root>/`. In this case the path info is
-`"/"` and the servlet path and context path is empty string (`+""+`).
+`"/"` and the servlet path is empty string (`+""+`).
 
 * A string containing only the `"/"`
 character indicates the "default" servlet of the application. In this