diff -ruP mock-autocache-diff/mock.py mock-autocache-permfix/mock.py
--- mock-autocache-diff/mock.py	2006-05-16 23:19:18.000000000 -0500
+++ mock-autocache-permfix/mock.py	2006-05-19 14:57:50.000000000 -0500
@@ -644,11 +644,39 @@
             fo.close()
 
     def _make_our_user(self):
+        if not os.path.exists(os.path.join(self.rootdir, 'usr/sbin/useradd')):
+            raise RootError, "Could not find useradd in chroot, maybe the install failed?"
         # should check if the user exists first
         # make the buildusers/groups
+        need_add_user = 0
         if not os.path.exists(self.rootdir + self.homedir):
-            if not os.path.exists(os.path.join(self.rootdir, 'usr/sbin/useradd')):
-                raise RootError, "Could not find useradd in chroot, maybe the install failed?"
+            need_add_user = 1
+        else:
+            # check for the following conditions:
+            #  -- using cache and current user is different from original cache creator
+            #  -- using --no-clean and current user is different from original creator
+            curruid = self.config['chrootuid']
+            chrootuid = None
+            passwd = os.path.join(self.rootdir, 'etc', 'passwd')
+
+            # find UID used to set up buildroot
+            fd = open( passwd, "r" )
+            while 1:
+                line = fd.readline()
+                if line == "": break
+                if line.startswith(self.config["chrootuser"]): 
+                    chrootuid = int(line.split(":")[2])
+
+            # do fixups if they are different
+            # if uid is different, assume we need to fix gid also
+            if chrootuid is not None and curruid != chrootuid:
+                need_add_user = 1
+                self.do_chroot('/usr/sbin/userdel -r %s' % self.config["chrootuser"], fatal = False)
+                self.do_chroot('/usr/sbin/groupdel %s' % self.config["chrootgroup"], fatal = False)
+                self.do_chroot('chown -R %s.%s %s' % (self.config["chrootuid"], self.config["chrootgid"], self.config["chroothome"]), fatal = False)
+                # may need a few other chown here if there are other files that have to be edited
+
+        if need_add_user:
             cmd = '/usr/sbin/useradd -m -u %s -d %s %s' % (self.config['chrootuid'], 
                     self.homedir, self.config['chrootuser'])
             self.do_chroot(cmd, fatal = True)