apt-get source report dead links to git://git.debian.org

[Norbert]

Steps to reproduce:
1. Try to obtain source code of some package - for example for FreeMat with `apt-get source freemat`
2. Get console output:

 Reading package lists... Done
 Building dependency tree
 Reading state information... Done
 NOTICE: 'freemat' packaging is maintained in the 'Git' version control system at:
 git://git.debian.org/debian-science/packages/freemat.git
 Need to get 38,1 MB of source archives.
 Get:1 http://archive.ubuntu.com/ubuntu/ trusty/universe freemat 4.0-5build1 (dsc) [2 139 B]
 Get:2 http://archive.ubuntu.com/ubuntu/ trusty/universe freemat 4.0-5build1 (tar) [38,0 MB]
 Get:3 http://archive.ubuntu.com/ubuntu/ trusty/universe freemat 4.0-5build1 (diff) [12,6 kB]
 Fetched 38,1 MB in 22s (1 727 kB/s)
 gpgv: Signature made Sat. 21 Dec. 2013 06:57:14 MSK using RSA key ID EA330543
 gpgv: Can't check signature: public key not found
 dpkg-source: warning: failed to verify signature on ./freemat_4.0-5build1.dsc
 dpkg-source: info: extracting freemat in freemat-4.0
 dpkg-source: info: unpacking freemat_4.0.orig.tar.gz
 dpkg-source: info: unpacking freemat_4.0-5build1.debian.tar.gz
 dpkg-source: info: applying 01_gcc_includes.patch
 dpkg-source: info: applying 07_fix_FTBFS_with_GCC_4.4.patch
 dpkg-source: info: applying 09_warning.patch
 dpkg-source: info: applying 10_llvm.patch
 dpkg-source: info: applying gcc4.5.patch
 dpkg-source: info: applying 11_ftbfs_qt48.patch

3. Try to get source code manually with `git` command

   $ git clone git://git.debian.org/debian-science/packages/freemat.git
   Cloning into 'freemat'...
   fatal: unable to connect to git.debian.org:
   git.debian.org[0: 194.177.211.202]: errno=Connection refused
   git.debian.org[1: 2001:648:2ffc:deb::211:202]: errno=Network is unreachable

Expected results:
* `apt-get source ...` reports correct link for the source code, user is able to get the source code manually.

Actual results:
* `apt-get source ...` reports wrong link for the source code, user is unable to get the source code manually.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: apt 1.0.1ubuntu2.18
ProcVersionSignature: Ubuntu 3.13.0-153.203-generic 3.13.11-ckt39
Uname: Linux 3.13.0-153-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.29
Architecture: amd64
CurrentDesktop: MATE
Date: Sun Jan 20 20:06:41 2019
InstallationDate: Installed on 2018-07-22 (181 days ago)
InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Release amd64 (20140417)
SourcePackage: apt
UpgradeStatus: No upgrade log present (probably fresh install)

[Rhonda D'Vine (rhonda)]

Packages get updated and their source moved. Within Debian, the old git hosting infrastructure got replaced by the gitlab instance on https://salsa.debian.org/. Given that there is not really a default schema where/how packages moved, redirects aren't an option. Older packages in the pool don't get updated for that, and only updated packages have current information again. Thus this is a wontfix or rather "will-fix-itself-over-time".