(June 2018)
PPA for tortoise is gone and Tortoise is removed when mercurial is updated.
If you're ok having an old version of Mercurial, you can reinstall following this guide:
First let's see the requirements:
sudo apt-get install tortoisehg
The following packages have unmet dependencies:
tortoisehg : Depends: mercurial (< 3.10~) but 4.4.1~xenial1 is to be installed
E: Unable to correct problems, you have held broken packages.
Required version: mercurial (< 3.10~)
sudo apt-get remove mercurial mercurial-common
$ apt-cache policy mercurial
mercurial:
Installed: (none)
Candidate: 4.4.1~xenial1
Version table:
4.4.1~xenial1 500
500 http://ppa.launchpad.net/mercurial-ppa/releases/ubuntu xenial/main amd64 Packages
3.9.1-0~16.04~ppa0 500
500 http://ppa.launchpad.net/jacob/hg/ubuntu xenial/main amd64 Packages
3.7.3-1ubuntu1 500
500 http://archive.ubuntu.com/ubuntu xenial/universe amd64 Packages
The best matching version is 3.9...
You will need the whole version number, just select and wheel/middle button click or copy-paste it.
$ sudo apt-get install mercurial=3.9.1-0~16.04~ppa0
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
mercurial : Depends: mercurial-common (= 3.9.1-0~16.04~ppa0) but it is not going to be installed
E: Unable to correct problems, you have held broken packages.
We're also missing mercurial-common. Let's find the matching available version.
$ apt-cache policy mercurial-common
mercurial-common:
Installed: 4.4.1~xenial1
Candidate: 4.4.1~xenial1
Version table:
*** 4.4.1~xenial1 500
500 http://ppa.launchpad.net/mercurial-ppa/releases/ubuntu xenial/main amd64 Packages
500 http://ppa.launchpad.net/mercurial-ppa/releases/ubuntu xenial/main i386 Packages
100 /var/lib/dpkg/status
3.9.1-0~16.04~ppa0 500
500 http://ppa.launchpad.net/jacob/hg/ubuntu xenial/main amd64 Packages
500 http://ppa.launchpad.net/jacob/hg/ubuntu xenial/main i386 Packages
3.7.3-1ubuntu1 500
500 http://archive.ubuntu.com/ubuntu xenial/universe amd64 Packages
500 http://archive.ubuntu.com/ubuntu xenial/universe i386 Packages
Copy the version, now let's install all.
Don't forget to update the versions by doing the previous steps, if the package manager cannot find your version it will not work.
$ sudo apt-get install mercurial=3.9.1-0~16.04~ppa0 mercurial-common=3.9.1-0~16.04~ppa0
# Now install as usual
$ sudo apt-get install tortoisehg
Tortoisehg should be available again.
Glad it did, good luck in your dev adventures in Linux. I'm sure you'll love it