Dependency issues while installing gcc 7.3 from Jonathon F's PPA

It seems that gcc-7 (7.3) is broken in Jonathon F's GCC 7.3 PPA. I can't install GCC 7.3 on clean Xenial system (without any other PPA):

$ sudo add-apt-repository -y ppa:jonathonf/gcc-7.3
$ sudo apt-get update
$ sudo apt-get install gcc-7
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:
 gcc-7 : Depends: libcc1-0 (>= 7.3.0-5ubuntu1~16.04.york0) but 5.4.0-6ubuntu1~16.04.9 is to be installed
         Depends: binutils (>= 2.28) but 2.26.1-1ubuntu1~16.04.6 is to be installed
         Depends: libgcc-7-dev (= 7.3.0-5ubuntu1~16.04.york0) but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

$ grep -r ppa /etc/apt/sources.list*
/etc/apt/sources.list.d/jonathonf-ubuntu-gcc-7_3-xenial.list:deb http://ppa.launchpad.net/jonathonf/gcc-7.3/ubuntu xenial main
/etc/apt/sources.list.d/jonathonf-ubuntu-gcc-7_3-xenial.list:# deb-src http://ppa.launchpad.net/jonathonf/gcc-7.3/ubuntu xenial main

So you should purge this PPA and use gcc 7.2 from “PPA for Ubuntu Toolchain Uploads (restricted)” team:

sudo apt-get install ppa-purge
sudo ppa-purge ppa:jonathonf/gcc-7.3
sudo add-apt-repository ppa:ubuntu-toolchain-r/test
sudo apt-get update
sudo apt-get install gcc-7
sudo apt-get install -f

Then contact Jonathon F and inform him about the problem.

Update. But I found other PPA ppa:jonathonf/gcc from Jonathon F. I can install gcc 7.3 from it.

#sudo ppa-purge ppa:ubuntu-toolchain-r/test # remove starting # if PPA added before
#sudo ppa-purge ppa:jonathonf/gcc-7.3 # remove starting # if PPA added before
sudo add-apt-repository -y ppa:jonathonf/gcc
sudo apt-get update
sudo apt-get install gcc-7 # will install 7.3.0-5ubuntu1~16.04.york0

and even gcc-8 (version 8-20180218-1ubuntu1~16.04.york0).