fixed an issue Bantle reported:

--------------
Hello,
I have the same problem: I have only one user in the people and no
e-mail for broken builds to the checkin user. The reason seams to be
that our SVN users have the following structure: WINDOWSDOMAIN\UserName
(with back slash). Hudson knows the user who checked in (e.g.:
WINDOWSDOMAIN\UserName).Hudson tries to create a folder with this name
in HUDSON_HOME/users/, and that is not possible with the back slash on
Windows! On Linux it is possible to create a directory with this name,
but Hudson (TomCat) can not find this directory. Do you have a solution
for this problem? Can you cast the back slash for the Windows domain
name in Hudson?
Thomas


git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@1273 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/java/hudson/model/User.java

@@ -175,7 +175,8 @@ public class User extends AbstractModelObject {
      * The file we save our configuration.
      */
     protected final XmlFile getConfigFile() {
-        return new XmlFile(XSTREAM,new File(Hudson.getInstance().getRootDir(),"users/"+ id +"/config.xml"));
+        String safeId = id.replace('\\', '_').replace('/', '_');
+        return new XmlFile(XSTREAM,new File(Hudson.getInstance().getRootDir(),"users/"+ safeId +"/config.xml"));
     }
 
     /**