doctrine/doctrine2 — pull request #846 by terraqout (2013-11-14 09:04:48+00:00)
Title: joinColumn is not required in manyToMany

in annotation you can don't write columns names:

/**
* @ManyToMany(targetEntity="Group", inversedBy="users")
* @JoinTable(name="users_groups")
*/

but in yaml you should:

manyToMany:
groups:
targetEntity: Group
inversedBy: users
joinTable:
name: users_groups
joinColumns:
user_id:
referencedColumnName: id
inverseJoinColumns:
group_id:
referencedColumnName: id

this patch fixes this unexpected behavior