Ruby 1.8.7 and 1.9.2 raise an exception upon URI URI "http://example"

lib/mechanize/http/auth_store.rb

@@ -38,7 +38,7 @@ def initialize
   # 2617.  If +domain+ is given it is only used for NTLM authentication.
 
   def add_auth uri, user, pass, realm = nil, domain = nil
-    uri = URI uri
+    uri = URI uri unless URI === uri
 
     raise ArgumentError,
           'NTLM domain given with realm which NTLM does not use' if
@@ -90,7 +90,7 @@ def credentials? uri, challenges
   # Retrieves credentials for +realm+ on the server at +uri+.
 
   def credentials_for uri, realm
-    uri = URI uri
+    uri = URI uri unless URI === uri
 
     uri += '/'
 
@@ -104,7 +104,7 @@ def credentials_for uri, realm
   # set all credentials for the server at +uri+ are removed.
 
   def remove_auth uri, realm = nil
-    uri = URI uri
+    uri = URI uri unless URI === uri
 
     uri += '/'