Steps to reproduce:
1. Install Ubuntu 16.04 LTS.
2. Install `muon` and `muon-discover` packages.
3. Launch Muon.
4. Try to get changelog for official package which is available in repositories (such as `samba`, `cups`, `smbclient`, `winbind`) - select package and click on "Changes List" tab.
5. Get the following text instead if changelog:
"The list of changes is not yet available. Please use Launchpad instead."
or
"ver: Apache
X-Content-Type-Options: nosniff
X-Frame-Options: sameorigin
Referrer-Policy: no-referrer
X-Xss-Protection: 1
Strict-Transport-Security: max-age=15552000
Public-Key-Pins: pin-sha256="br+Uf2+rkmMOzm4/4dHqwGyRXuGk1LC9DdGPIS0iPuU="; pin-sha256="0RzGS6yWFFS8w3jZZjWuXYwUXfELYh7KxcTmtlw0EMs="; max-age=5184000
Content-Length: 331
Keep-Alive: timeout=5, max=100
Connection: Keep-Alive
Content-Type: text/html; charset=iso-8859-1
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
<html><head>
<title>404 Not Found</title>
</head><body>
<h1>Not Found</h1>
<p>The requested URL /changelogs/pool/main/c/cups/cups_2.1.3-4ubuntu0.3/changelog.txt was not found on this server.</p>
<hr>
<address>Apache Server at packages.debian.org Port 443</address>
</body></html>
HTTP/1.1 404 Not Found
Date: Fri, 01 Sep 2017 11:51:11 GMT
Server: Apache
X-Content-Type-Options: nosniff
X-Frame-Options: sameorigin
Referrer-Policy: no-referrer
X-Xss-Protection: 1
Strict-Transport-Security: max-age=15552000
Public-Key-Pins: pin-sha256="br+Uf2+rkmMOzm4/4dHqwGyRXuGk1LC9DdGPIS0iPuU="; pin-sha256="0RzGS6yWFFS8w3jZZjWuXYwUXfELYh7KxcTmtlw0EMs="; max-age=5184000
Content-Length: 331
Keep-Alive: timeout=5, max=99
Connection: Keep-Alive
Content-Type: text/html; charset=iso-8859-1
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
<html><head>
<title>404 Not Found</title>
</head><body>
<h1>Not Found</h1>
<p>The requested URL /changelogs/pool/main/c/cups/cups_2.1.3-4ubuntu0.3/changelog.txt was not found on this server.</p>
<hr>
<address>Apache Server at packages.debian.org Port 443</address>
</body></html>"
Expected results:
Muon is able to show changelog for packages.
Actual results:
Muon is unable to show changelog for packages.
Notes:
1. `apt-get changelog samba cups` returns changelog from http://changelogs.ubuntu.com as expected.
2. It seems that Muon was incorectly setup after importing from Debian.
Status changed to 'Confirmed' because the bug affects multiple users.