ceph-deploy error : GPG error trusty InRelease: Clearsigned file isn’t valid, got ‘NODATA’

Just tried to install ceph hammer version on ubuntu 14.04.5 for test purposes. First of all ceph-deploy version newer than 1.5.25 doesn’t install hammer even you define “–release hammer” parameter.
So, I installed that version.
sudo pip install ceph-deploy==1.5.25
But, In this version the repo domain is defined as “ceph.com” and ceph-deploy adds the following line into apt sources.
deb https://ceph.com/debian-hammer/ trusty main

Now the problem is that ceph.com redirects to download.ceph.com. When ceph-deploy executes apt-get, apt-get will give GPG error as in the following example.

E: GPG error: http://ceph.com trusty InRelease: Clearsigned file isn't valid, got 'NODATA' (does the network require authentication?)
99% [1 Sources bzip2 0 B] [7 InRelease gpgv 618 B] [5 Packages 5489 kB/5859 kB Splitting up /var/lib/apt/lists/partial/ceph.com_debian-
hammer_dists_trusty_InReIgn http://ceph.com trusty InRelease

To accomplish it I edited the file below.
/usr/local/lib/python2.7/dist-packages/ceph_deploy/hosts/debian/install.py
Then find the line below and replace ceph.com with download.ceph.com. Afterwards, you should install ceph hammer packages on the nodes without GPG error.

if version_kind == 'stable':
url = 'http://ceph.com/debian-{version}/'.format(