Fixed the bundle run when the channel is None;

Also added a second retrial on the obtention of the bundle's origin (in
order to use both the normalized and non normalized channel -> this
because some charms cause a failure on obtaining the origin with one
type of channel, and others with the other one).

Signed-off-by: Pedro Escaleira <pedroescaleira@hotmail.com>

Author: oEscal

juju/bundle.py

@@ -584,11 +584,26 @@ async def run(self, context):
             options["trust"] = "true"
 
         url = URL.parse(str(charm))
+
+        # set the channel to the default value if not specified
+        if not self.channel:
+            if Schema.CHARM_STORE.matches(url.schema):
+                self.channel = "stable"
+            elif Schema.CHARM_HUB.matches(url.schema):
+                self.channel = "latest/stable"
+            else:   # for local charms
+                self.channel = ""
+
         channel = None
+        non_normalized_channel = None
         if self.channel is not None and self.channel != "":
-            channel = Channel.parse(self.channel).normalize()
+            non_normalized_channel = Channel.parse(self.channel)
+            channel = non_normalized_channel.normalize()
 
-        origin = context.origins.get(str(url), {}).get(str(channel), None)
+        origin = context.origins.get(str(url), {}).get(
+            str(channel),
+            context.origins.get(str(url), {}).get(str(non_normalized_channel), None),
+        )
         if origin is None:
             raise JujuError("expected origin to be valid for application {} and charm {} with channel {}".format(self.application, str(url), str(channel)))