b/11551107
This is caused by ImapConnection.doLogin() only throwing
AuthenticationFailedExceptions and not other varieties of exceptions.
While fixing this bug, I discovered that the ConversationListFooterView
that is displayed in response to a authentication failure contains a
button called "Sign In" that didn't actually do anything. I made it
navigate to the incoming account settings fragment where the user is
free to change the relevant account credentials.
Change-Id: I2c772ecab18f3e57059eceeae01de08f1fdab4c2
0dffe3afd7