pg9.4b1: unhelpful error message when creating a collation

sh> lsb_release -d
Description: Ubuntu 14.04 LTS
Codename: trusty

sh> uname -a
Linux sto 3.13.0-24-generic #47-Ubuntu SMP Fri May 2 23:30:00 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux

sh> locale -a
C
C.UTF-8
en_AG
en_AG.utf8
en_AU.utf8
en_BW.utf8
en_CA.utf8
en_DK.utf8
en_GB.utf8
en_HK.utf8
en_IE.utf8
en_IN
en_IN.utf8
en_NG
en_NG.utf8
en_NZ.utf8
en_PH.utf8
en_SG.utf8
en_US.utf8
en_ZA.utf8
en_ZM
en_ZM.utf8
en_ZW.utf8
fr_FR.utf8
POSIX

# with postgresql 9.4 installed from apt.postgresql.org.

sql> SELECT VERSION();
PostgreSQL 9.4beta1 on x86_64-unknown-linux-gnu, compiled by gcc (Ubuntu 4.8.2-19ubuntu1) 4.8.2, 64-bit

sql> \dOS+
+- same list as above with "locale"

sql> SHOW lc_messages;
en_US.UTF-8

# stuff which is working as expected:

sql> CREATE COLLATION "test0" (locale='C');
CREATE COLLATION

sql> CREATE COLLATION "test1" (locale='en_US.UTF-8');
CREATE COLLATION

sql> CREATE COLLATION "test2" (locale='en_US.UTF8');
CREATE COLLATION

sql> CREATE COLLATION "test3" (locale='Foo');
ERROR: could not create locale "test3": No such file or directory
DETAIL: The operating system could not find any locale data for the locale name "Foo".

# stuff which is incoherent:

sql> CREATE COLLATION "french" (locale='fr_FR.utf8');
ERROR: could not create locale "fr_FR.utf8": Success

The collation creation fails, not sure why yet. However, the "error ..
success" message is especially unhelpful.

Raising client_min_messages does not add more information.

I could not get the same error with 9.3.4.

--
Fabien.