ipa-client-install uninstall does not work on IPA server

When IPA server is being uninstalled, IPA client on-master
uninstallation which is called by the script fails.

https://fedorahosted.org/freeipa/ticket/1197

ipa-client/ipa-install/ipa-client-install

@@ -190,7 +190,7 @@ def uninstall(options, env):
         return 2
 
     server_fstore = sysrestore.FileStore('/var/lib/ipa/sysrestore')
-    if server_fstore.has_files():
+    if server_fstore.has_files() and not options.on_master:
         print "IPA client is configured as a part of IPA server on this system."
         print "Please refer to ipa-server-install for uninstallation."
         return 2