cannot configure bridges

When using code from tor master (Tor version 0.4.2.0-alpha-dev (git-d475d7c2fb3c0ed5), I cannot configure bridges in Tor Browser. This seems to be a very recent regression, probably caused by the changes in https://gitweb.torproject.org/tor.git/commit/?id=d475d7c2fb3c0ed5120c50011b187f6957a4f52c

The relevant portion of the control port conversation is:

SETCONF UseBridges=1 Bridge="obfs4 ..."
513 Unacceptable option value: You cannot set both UseBridges and EntryNodes.

As far as I can tell, EntryNodes is not present in any of my configuration.

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