package postgresql-8.4 8.4.18-0ubuntu12.04 failed to install/upgrade: subprocess installed post-installation script returned error exit status 1

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perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
 LANGUAGE = "es_AR:en",
 LC_ALL = (unset),
 LC_TIME = "es_MX.UTF-8",
 LC_MONETARY = "es_MX.UTF-8",
 LC_ADDRESS = "es_MX.UTF-8",
 LC_TELEPHONE = "es_MX.UTF-8",
 LC_NAME = "es_MX.UTF-8",
 LC_MEASUREMENT = "es_MX.UTF-8",
 LC_IDENTIFICATION = "es_MX.UTF-8",
 LC_NUMERIC = "es_MX.UTF-8",
 LC_PAPER = "es_MX.UTF-8",
 LANG = "es_AR.UTF-8"
    are supported and installed on your system.
perl: warning: Falling back to the standard locale ("C").
locale: Cannot set LC_CTYPE to default locale: No such file or directory
locale: Cannot set LC_MESSAGES to default locale: No such file or directory
locale: Cannot set LC_ALL to default locale: No such file or directory
Setting up postgresql-8.4 (8.4.18-0ubuntu12.04) ...
 * Starting PostgreSQL 8.4 database server * The PostgreSQL server failed to start. Please check the log output:
FATAL: invalid value for parameter "lc_messages": "es_MX.UTF8"
                                                                                                                                      [fail]
invoke-rc.d: initscript postgresql, action "start" failed.
dpkg: error processing postgresql-8.4 (--configure):
 subprocess installed post-installation script returned error exit status 1
Setting up postgresql-9.1 (9.1.10-0ubuntu12.04) ...
 * Starting PostgreSQL 9.1 database server * The PostgreSQL server failed to start. Please check the log output:
FATAL: invalid value for parameter "lc_messages": "es_MX.utf8"
                                                                                                                                      [fail]
invoke-rc.d: initscript postgresql, action "start" failed.
dpkg: error processing postgresql-9.1 (--configure):
 subprocess installed post-installation script returned error exit status 1
Errors were encountered while processing:
 postgresql-8.4
 postgresql-9.1
E: Sub-process /usr/bin/dpkg returned an error code (1)

ProblemType: Package
DistroRelease: Ubuntu 12.04
Package: postgresql-8.4 8.4.18-0ubuntu12.04
ProcVersionSignature: Ubuntu 3.2.0-55.85-generic 3.2.51
Uname: Linux 3.2.0-55-generic i686
ApportVersion: 2.0.1-0ubuntu17.6
Architecture: i386
Date: Wed Nov 6 15:26:29 2013
DuplicateSignature: package:postgresql-8.4:8.4.18-0ubuntu12.04:subprocess installed post-installation script returned error exit status 1
ErrorMessage: subprocess installed post-installation script returned error exit status 1
InstallationMedia: Ubuntu 10.04.1 LTS "Lucid Lynx" - Release i386 (20100816.1)
MarkForUpload: True
SourcePackage: postgresql-8.4
Title: package postgresql-8.4 8.4.18-0ubuntu12.04 failed to install/upgrade: subprocess installed post-installation script returned error exit status 1
UpgradeStatus: Upgraded to precise on 2013-10-24 (12 days ago)