package python 2.7.5-5ubuntu3 failed to install/upgrade: pre-dependency problem - not installing python

[Ana]

while updating to ubuntu 15.04

ProblemType: Package
DistroRelease: Ubuntu 15.04
Package: python 2.7.5-5ubuntu3
ProcVersionSignature: Ubuntu 3.13.0-74.118-generic 3.13.11-ckt30
Uname: Linux 3.13.0-74-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.19
Architecture: amd64
Date: Tue Dec 29 17:03:58 2015
DuplicateSignature: package:python:2.7.5-5ubuntu3:pre-dependency problem - not installing python
ErrorMessage: pre-dependency problem - not installing python
InstallationDate: Installed on 2013-08-20 (861 days ago)
InstallationMedia: Ubuntu 12.04.2 LTS "Precise Pangolin" - Release amd64 (20130213)
RelatedPackageVersions:
 dpkg 1.17.25ubuntu1.1
 apt 1.0.1ubuntu2.10
SourcePackage: python-defaults
Title: package python 2.7.5-5ubuntu3 failed to install/upgrade: pre-dependency problem - not installing python
UpgradeStatus: Upgraded to vivid on 2015-12-29 (0 days ago)