Do not set the mime-type for userdata

We set the mime-type to  'x-shellscript' for all
single userdata when user_data_format='SOFTWARE_CONFIG',
it's incorrect, for example, if user create a server
with a cloud-config userdata, we will set the mime-type to
'x-shellscript', then cloud-init will consume the userdata
as a shellscript and fail to execute.

This change will improve this by not setting the mime-type
and letting cloud-init figure it out from the first line
in the file.

Closes-Bug: #1643739
Change-Id: If026884a95c58bb81a0f04ab415909011b1a5414
diff --git a/scenario/test_server_signal.py b/scenario/test_server_signal.py
index 4567e43..b2085e2 100644
--- a/scenario/test_server_signal.py
+++ b/scenario/test_server_signal.py
@@ -20,13 +20,15 @@
 class ServerSignalIntegrationTest(scenario_base.ScenarioTestsBase):
     """Test a server in a created network can signal to heat."""
 
-    def test_server_signal(self):
+    def _test_server_signal(self, user_data_format='RAW',
+                            image=None):
         """Check a server in a created network can signal to heat."""
         parameters = {
             'key_name': self.keypair_name,
             'flavor': self.conf.minimal_instance_type,
-            'image': self.conf.minimal_image_ref,
+            'image': image,
             'timeout': self.conf.build_timeout,
+            'user_data_format': user_data_format
         }
 
         # Launch stack
@@ -72,3 +74,12 @@
             self._log_console_output(servers=[server])
             self.fail(
                 "Timed out waiting for %s to become reachable" % server_ip)
+
+    def test_server_signal_userdata_format_raw(self):
+        self._test_server_signal(image=self.conf.minimal_image_ref)
+
+    def test_server_signal_userdata_format_software_config(self):
+        if not self.conf.image_ref:
+            raise self.skipException("No image configured to test")
+        self._test_server_signal(user_data_format='SOFTWARE_CONFIG',
+                                 image=self.conf.image_ref)