Got it after a little poking around with git. Rolling back to a commit in my code before the one given here didn't didn't show this reproduce this.
$ php app/console doctrine:schema:create
ATTENTION: This operation should not be executed in a production environment.
Creating database schema...
Database schema created successfully!
$ git checkout d686a39fb664dca540167e1b3e96ea0ffd67bc00
Previous HEAD position was 0510a59... * First round of Customer-to-Accounts (1:n) mapping done * Start of Customer-to-Tn and Tn-to-Account mapping
HEAD is now at d686a39... * A little debugging for Entity::Customer::hasEntitlement * Add FK for Customer to Tn
$ php app/console doctrine:schema:update --dump-sql
ALTER TABLE Account CHANGE guid guid VARCHAR(255) NOT NULL;
ALTER TABLE Tn DROP FOREIGN KEY FK_3504C6F09B6B5FBA;
DROP INDEX IDX_3504C6F09B6B5FBA ON Tn;
ALTER TABLE Tn ADD tnType VARCHAR(10) NOT NULL, CHANGE account_id customer INT DEFAULT NULL;
ALTER TABLE Tn ADD CONSTRAINT FK_3504C6F07D3656A4 FOREIGN KEY (account) REFERENCES Account (id);
ALTER TABLE Tn ADD CONSTRAINT FK_3504C6F081398E09 FOREIGN KEY (customer) REFERENCES Customer (id);
CREATE INDEX IDX_3504C6F07D3656A4 ON Tn (account);
CREATE INDEX IDX_3504C6F081398E09 ON Tn (customer);
ALTER TABLE Customer CHANGE guid guid VARCHAR(255) NOT NULL, CHANGE authGuid authGuid VARCHAR(255) NOT NULL
mah@debian:~/comcast$ php app/console doctrine:schema:update --force
Updating database schema...
[Doctrine\DBAL\DBALException]
An exception occurred while executing 'ALTER TABLE Tn ADD CONSTRAINT FK_3504C6F07D3656A4 FOREIGN KEY (account)
REFERENCES Account (id)':
SQLSTATE[42000]: Syntax error or access violation: 1072 Key column 'account' doesn't exist in table
[PDOException]
SQLSTATE[42000]: Syntax error or access violation: 1072 Key column 'account' doesn't exist in table
doctrine:schema:update [--complete] [--dump-sql] [--force] [--em[="..."]]
$ php app/console doctrine:schema:update --dump-sql
ALTER TABLE Account CHANGE guid guid VARCHAR(255) NOT NULL;
ALTER TABLE Tn ADD account INT DEFAULT NULL;
ALTER TABLE Tn ADD CONSTRAINT FK_3504C6F07D3656A4 FOREIGN KEY (account) REFERENCES Account (id);
ALTER TABLE Tn ADD CONSTRAINT FK_3504C6F081398E09 FOREIGN KEY (customer) REFERENCES Customer (id);
CREATE INDEX IDX_3504C6F07D3656A4 ON Tn (account);
CREATE INDEX IDX_3504C6F081398E09 ON Tn (customer);
ALTER TABLE Customer CHANGE guid guid VARCHAR(255) NOT NULL, CHANGE authGuid authGuid VARCHAR(255) NOT NULL
$ php app/console doctrine:schema:update --force
Updating database schema...
Database schema updated successfully! "7" queries were executed
$
Please run the command with the --dump-sql option instead of --force each time before launching it for real, to be able to see which SQL queries are executed in both cases