ecrist reported in irc that he had a user with a uid of [u'ecrist',u'4']

This was done and easily reproducible with:

$ ipa user-mod ecrist userid=4

userid is an alias for uid in the schema.

If you substitute the above command uid instead of userid you'd get:

ipa: ERROR: uid; Only one value allowed

I reproduced it very easily.

Note that this isn't a multi-valued field, it is literally a converted list stored as the attribute:

$ ldapsearch -Y GSSAPI givenname=tim
dn: uid=[u'tuser1'\2C u'4'],cn=users,cn=accounts,dc=example,dc=com
...
krbCanonicalName: [u'tuser1', u'4']@EXAMPLE.COM
homeDirectory: /home/tuser1
mail: tuser1@example.com
krbPrincipalName: [u'tuser1', u'4']@EXAMPLE.COM
mepManagedEntry: cn=[u'tuser1'\2C u'4'],cn=groups,cn=accounts,dc=example,dc=com
uid: [u'tuser1', u'4']