Using pidgin from the command-line or launching it via the indicator is not working. I've tried reinstalling it, but the issue persists:

$ pidgin

The program 'pidgin' is currently not installed. You can install it by typing:

sudo apt-get install pidgin

$ sudo apt-get install pidgin

Reading package lists... Done

Building dependency tree       

Reading state information... Done

pidgin is already the newest version.

The following package was automatically installed and is no longer required:

  gstreamer0.10-ffmpeg

Use 'apt-get autoremove' to remove it.

0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

How can this be fixed?

Update: removing pidgin-sipe did not help remove the diversion (see answers below). Doing sudo dpkg-divert --remove /usr/bin/pidgin, and then reinstalling the pidgin package fixed it.