suite.py: Fix typo in variable name used during exception

Fixes a possible double exception introduced in 0ffb4144

Change-Id: I44a30f51c23e6a57ccae3483c806c0ed25d2ecf9
diff --git a/src/osmo_gsm_tester/suite.py b/src/osmo_gsm_tester/suite.py
index 64de2db..0664897 100644
--- a/src/osmo_gsm_tester/suite.py
+++ b/src/osmo_gsm_tester/suite.py
@@ -130,7 +130,7 @@
                 ftype = type(e).__name__
                 fmsg = repr(e) + '\n' + traceback.format_exc().rstrip()
                 if isinstance(e, resource.NoResourceExn):
-                    msg += '\n' + 'Current resource state:\n' + repr(suite_run.reserved_resources)
+                    fmsg += '\n' + 'Current resource state:\n' + repr(suite_run.reserved_resources)
             self.set_fail(ftype, fmsg, False)
 
         finally: