[schema] [manual] Add colors to the subscription model.

This is preparatory for removing the StreamColor model, so we also set
things up so anything changing the StreamColor model changes the
Subscription model too.

The manual task is to run the copy_colors.py management command after
deployment to each of staging and prod.

(imported from commit 1be7523ca59f5266eb2c4dc2009e31209ed49635)

zephyr/lib/actions.py

@@ -431,13 +431,16 @@ def set_stream_color_backend(user_profile, subscription, color=None):
     if not created:
         stream_color.color = color
         stream_color.save(update_fields=["color"])
+        subscription.color = color
+        subscription.save(update_fields=["color"])
     return color
 
 def do_add_subscription(user_profile, stream, no_log=False):
     recipient = get_recipient(Recipient.STREAM, stream.id)
+    color = pick_color(user_profile)
     (subscription, created) = Subscription.objects.get_or_create(
         user_profile=user_profile, recipient=recipient,
-        defaults={'active': True})
+        defaults={'active': True, 'color': color})
     did_subscribe = created
     if not subscription.active:
         did_subscribe = True