Eu usei o comando:
sudo apt-get install mercurial mercurial-common
Resultado:
The following packages have unmet dependencies:
mercurial : Depends: mercurial-common (= 4.0.2~trusty1) but 4.1~rc~trusty1 is to be installed
mercurial-common : Recommends: mercurial (= 4.1~rc~trusty1) but 4.0.2~trusty1 is to be installed
Breaks: mercurial (< 4.1~rc~trusty1) but 4.0.2~trusty1 is to be installed
E: Unable to correct problems, you have held broken packages.
Remove mercurial-comum, instalado Mercurial novamente - não ajudou.