Rule does not return matched parameter value when it starts with "?"

[GoogleCodeExporter]

What steps will reproduce the problem?

1. With the following rule

<rule>
       <from>^/users/(.*)$</from>
       <to last="true">/users.do?&amp;=$1
 </rule>

2. and the following url:

http://localhost:8077/users/?idUser=1

the parameter $1 value is empty.

3. Although if we use the following url: 

http://localhost:8077/users/idUser=1

the parameter $1 value is "idUser=1". 

The version is UrlRewrite 3.2

Original issue reported on code.google.com by fbla...@gmail.com on 20 Feb 2012 at 6:56