Firefox resets homepage to https://start.ubuntu-mate.org when trying to use about:newtab as homepage.

[WolphFang]

When setting the home page to "about:newtab" under about:preferences, the setting works until exit, and restarting Firefox, at which in time the home page value is overwritten to the distribution default of value "https://start.ubuntu-mate.org".

ProblemType: Bug
DistroRelease: Ubuntu 17.04
Package: firefox 50.1.0+build2-0ubuntu1
ProcVersionSignature: Ubuntu 4.10.0-14.16-generic 4.10.3
Uname: Linux 4.10.0-14-generic x86_64
ApportVersion: 2.20.4-0ubuntu2
Architecture: amd64
BuildID: 20161213225349
CurrentDesktop: MATE
Date: Sun Apr 2 11:40:04 2017
InstallationDate: Installed on 2014-05-08 (1059 days ago)
InstallationMedia: Linux Mint 16 "petra" - Release amd64 20131126
SourcePackage: firefox
UpgradeStatus: Upgraded to zesty on 2017-03-15 (18 days ago)