quotes qop value prior to parsing

it is very common for this header to contain this value unquoted

lib/httparty/net_digest_auth.rb

@@ -44,7 +44,10 @@ module Net
     private
 
       def parse(response_header)
-        response_header['www-authenticate'] =~ /Digest (.*)/
+        header = response_header['www-authenticate']
+          .gsub(/qop=(auth(?:-int)?)/, %Q(qop="\\1"))
+
+        header =~ /Digest (.*)/
         params = {}
         $1.gsub(/(\w+)="(.*?)"/) { params[$1] = $2 }
         params

spec/httparty/net_digest_auth_spec.rb

@@ -75,6 +75,17 @@ describe Net::HTTPHeader::DigestAuthenticator do
     end
   end
 
+  context "when quality of protection (qop) is unquoted" do
+    before do
+      @digest = setup_digest({
+        'www-authenticate' => 'Digest realm="myhost@testrealm.com", nonce="NONCE", qop=auth',
+      })
+    end
+
+    it "should still set qop" do
+      authorization_header.should include(%Q(qop="auth"))
+    end
+  end
 
   context "with unspecified quality of protection (qop)" do
     before do