fix(tap): set clone remote name to origin explicitly

Git now allows setting a different default remote name than `origin`
when you do a fresh clone by running:

```shell
git config --global clone.defaultRemoteName notorigin
```

This causes `brew tap <tap_name> && brew update` to fail, as it clones
with a different remote name in the `tap` and then expects the remote to
be `origin` in the `update`.

Fix this by explicitly setting the origin remote in the clone command.

Library/Homebrew/tap.rb

@@ -296,6 +296,10 @@ class Tap
 
     $stderr.ohai "Tapping #{name}" unless quiet
     args =  %W[clone #{requested_remote} #{path}]
+
+    # Override possible user configs like:
+    #   git config --global clone.defaultRemoteName notorigin
+    args << "--origin=origin"
     args << "--depth=1" unless full_clone
     args << "-q" if quiet