So, I found check_signatures in my ~/.bazaar/bazaar.conf
I changed it to say 'create_signatures' instead of 'check_signatures', and I get this error:
bzr: ERROR: Invalid signing policy 'require'
The line in bazaar.conf is "check_signatures=require".
I tried changing it to "create_signatures=yes" and I get an error:
bzr: ERROR: Invalid signing policy 'yes'
I'm going to set this back the way it was, as I prefer to see warnings than to be unable to work. The warning message should say what the new value of 'create_signatures' should be, based on the old value of 'check_signatures', or at least tell me where I can find out what the new value should be.