Add caller to v1 image_client wait_for_image_status timeout exception

This will help in fingerprinting race failures with logstash so that we
can uniquely identify the same error message but between different tests
that are failing, then we can see trends over time.

Related-Bug: #1289546

Change-Id: Iaeeaef6f9235cd8c6f7fa4dae3424542b708ad2b
diff --git a/tempest/services/image/v1/json/image_client.py b/tempest/services/image/v1/json/image_client.py
index 2353908..4a7c163 100644
--- a/tempest/services/image/v1/json/image_client.py
+++ b/tempest/services/image/v1/json/image_client.py
@@ -22,6 +22,7 @@
 
 from tempest.common import glance_http
 from tempest.common import rest_client
+from tempest.common.utils import misc as misc_utils
 from tempest import config
 from tempest import exceptions
 from tempest.openstack.common import log as logging
@@ -297,6 +298,9 @@
                            'while waiting for %s, '
                            'but we got %s.' %
                            (self.build_timeout, status, value))
+                caller = misc_utils.find_test_caller()
+                if caller:
+                    message = '(%s) %s' % (caller, message)
                 raise exceptions.TimeoutException(message)
             time.sleep(self.build_interval)
             old_value = value