I suggest to not use any Pascal .deb at all, rather use fcpup which works sometimes:
[2016-10-01 21:34:59.458 Info] 1-10-16 21:34:59: fpcup fpcup001 (20150210) started.
[2016-10-01 21:35:00.313 Info] SVN client found: /usr/bin/svn
[2016-10-01 21:35:53.188 Info] TFPCInstaller init:
[2016-10-01 21:35:53.188 Info] Bootstrap compiler dir: /home/demo/development/fpcbootstrap/
[2016-10-01 21:35:53.188 Info] FPC URL:
http://svn.freepascal.org/svn/fpc/tags/release_3_0_0
[2016-10-01 21:35:53.188 Info] FPC options:
[2016-10-01 21:35:53.188 Info] FPC directory: /home/demo/development/fpc
[2016-10-01 21:35:53.188 Info] External program path: /home/demo/development/fpc/bin/x86_64-linux:/home/demo/development/fpc/bin:/home/demo/development/fpc/utils:/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games:/sbin:/usr/sbin
[2016-10-01 21:35:53.589 Info] INFO: directory /home/demo/development/fpc is not an SVN repository (or a repository with the wrong remote URL).
[2016-10-01 21:35:53.789 Info] INFO: creating directory /home/demo/development/fpc for SVN checkout.
[2016-10-01 21:40:53.858 Info] FPC: update succeeded.
[2016-10-01 21:40:53.858 Info] 1-10-16 21:40:53: fpcup finished.
[2016-10-01 21:40:54.058 Info] ------------------------------------------------