软件包删除失败。postgresql-contrib-9.1：安装的子进程删除前脚本返回错误退出状态 127

Question

Do you want to continue? [Y/n] y
(Reading database ... 404522 files and directories currently installed.)
Removing postgresql-contrib-9.1 (9.1.15-0ubuntu0.12.04) ...
/var/lib/dpkg/info/postgresql-contrib-9.1.prerm: 11: /var/lib/dpkg/info/postgresql-contrib-9.1.prerm: remove_contrib_version: not found
dpkg: error processing package postgresql-contrib-9.1 (--remove):
 subprocess installed pre-removal script returned error exit status 127
Errors were encountered while processing:
 postgresql-contrib-9.1
E: Sub-process /usr/bin/dpkg returned an error code (1)

和

dpkg --remove --force-remove-reinstreq postgresql-contrib-9.1

是一样的。