Hi,

This patch updates fish shell to 3.0.0.

I tested this patch on my computer.  It seems bug#30265
(https://lists.gnu.org/archive/html/bug-guix/2018-01/msg00296.html) has
gone.

* gnu/packages/shells.scm (fish): Update to 3.0.0.
  [source]: Remove dead URL.
  [inputs]: Remove bc.  Replace python-wrapper with python.
  [arguments]: Remove configure-flags.  Add multiple phases to patch fish.
  Enable fish to source /etc/fish/config.sh.  Add user's and system's guix
  profiles to __extra_* variables.