Bug 1411688 - Part 3: Set MOZ_UPDATE_CHANNEL in single-locale repacks. r=aki

I'm seeing "try" in my repacks, when the underlying build has
"nightly-try".  This should make the two agree.

MozReview-Commit-ID: 45yE9Qwz0v7

--HG--
extra : rebase_source : ff1ae4e50203ea032032069203558d75d348ff21

testing/mozharness/scripts/mobile_l10n.py

@@ -187,6 +187,20 @@ class MobileSingleLocale(MockMixin, LocalesMixin, ReleaseMixin,
         if 'MOZ_SIGNING_SERVERS' in os.environ:
             repack_env['MOZ_SIGN_CMD'] = \
                 subprocess.list2cmdline(self.query_moz_sign_cmd(formats=['jar']))
+
+        if self.query_is_nightly() or self.query_is_nightly_promotion():
+            if self.query_is_nightly():
+                # Nightly promotion needs to set update_channel but not do all
+                # the 'IS_NIGHTLY' automation parts, like uploading symbols
+                # (for now).
+                repack_env["IS_NIGHTLY"] = "yes"
+            # In branch_specifics.py we might set update_channel explicitly.
+            if c.get('update_channel'):
+                repack_env["MOZ_UPDATE_CHANNEL"] = c['update_channel']
+            else:  # Let's just give the generic channel based on branch.
+                repack_env["MOZ_UPDATE_CHANNEL"] = \
+                    "nightly-%s" % (c['branch'],)
+
         self.repack_env = repack_env
         return self.repack_env