Fix error message order, add test

Fixed some error message logic. Previously, a tool_destinations.yml config
with an empty priority key in global 'default_destination' would throw two
errors in a strange order; one about no valid default priority destinations,
and another about no default destination. This has been changed so with the
same config there is now just a 'No default destinations in config' message.

Also added a test that confirms this behaviour

lib/galaxy/jobs/dynamic_tool_destination.py

@@ -842,37 +842,37 @@ def infinite_defaultdict():
                         if verbose:
                             log.debug(error)
                         valid_config = False
-
-                else:
-                    error = "No default priority destinations specified in config!"
-                    if verbose:
-                        log.debug(error)
-                    valid_config = False
-
-                if 'default_priority' in obj:
-                    if isinstance(obj['default_priority'], str):
-                        if obj['default_priority'] in priority_list:
-                            new_config['default_priority'] = obj['default_priority']
+                    else:
+                        if 'default_priority' in obj:
+                            if isinstance(obj['default_priority'], str):
+                                if obj['default_priority'] in priority_list:
+                                    new_config['default_priority'] = obj['default_priority']
+                                else:
+                                    error = ("Default priority '" + str(obj['default_priority'])
+                                             + "' is not a valid priority.")
+                                    if verbose:
+                                        log.debug(error)
+                            else:
+                                error = "default_priority in config is not valid."
+                                if verbose:
+                                    log.debug(error)
+                                valid_config = False
                         else:
-                            error = ("Default priority '" + str(obj['default_priority'])
-                                     + "' is not a valid priority.")
+                            error = "No default_priority section found in config."
+                            if 'med' in priority_list:
+                                error += " Setting 'med' as default priority."
+                                new_config['default_priority'] = 'med'
+                            else:
+                                error += " Things may not run as expected!"
+                                valid_config = False
                             if verbose:
                                 log.debug(error)
-                    else:
-                        error = "default_priority in config is not valid."
-                        if verbose:
-                            log.debug(error)
-                        valid_config = False
+
                 else:
-                    error = "No default_priority section found in config."
-                    if 'med' in priority_list:
-                        error += " Setting 'med' as default priority."
-                        new_config['default_priority'] = 'med'
-                    else:
-                        error += " Things may not run as expected!"
-                        valid_config = False
+                    error = "No global default destinations specified in config!"
                     if verbose:
                         log.debug(error)
+                    valid_config = False
             else:
                 error = "No global default destination specified in config!"
                 if verbose:

test/unit/jobs/dynamic_tool_destination/test_dynamic_tool_destination.py

@@ -769,6 +769,15 @@ def test_tool_default_destination_without_priority_not_in_job_conf(self, l):
             ('galaxy.jobs.dynamic_tool_destination', 'DEBUG', 'Finished config validation.')
         )
 
+    @log_capture()
+    def test_tool_default_destination_without_priority_not_in_job_conf(self, l):
+        dt.parse_yaml(path=yt.ivYMLTest162, job_conf_path=job_conf_path, test=True)
+        l.check(
+            ('galaxy.jobs.dynamic_tool_destination', 'DEBUG', 'Running config validation...'),
+            ('galaxy.jobs.dynamic_tool_destination', 'DEBUG', "No global default destinations specified in config!"),
+            ('galaxy.jobs.dynamic_tool_destination', 'DEBUG', 'Finished config validation.')
+        )
+
 # ================================Valid yaml files==============================
     @log_capture()
     def test_parse_valid_yml(self, l):

test/unit/jobs/dynamic_tool_destination/ymltests.py

@@ -1162,3 +1162,9 @@
             med: waffles_default
     verbose: True
 '''
+# Nothing in the priority dict
+ivYMLTest162 = '''
+    default_destination:
+      priority:
+    verbose: True
+'''