load Rails environment before forking
load Rails environment before forking

refs FOO-966

before g/247902, the canvas:compile_assets task was running css:compile
in a thread and not in a forked process, and by forking, we're confusing
Rake into not running some of the prerequisite tasks (like :environment)
in the forked process

  TEST PLAN
\ ---- ----

- you can still run "bundle exec rake canvas:compile_assets"
- if you create a migration in the future, you should receive a relevant
  error message and not "undefined constant"

Change-Id: I8f24562eddf7ed1a2e8ca2d3914f7c2f24e60a90
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/249117
Tested-by: Service Cloud Jenkins <9144042a601061f88f1e1d7a1753ea3e2972119d@instructure.com>
Reviewed-by: James Butters <4c5a489c9bb72d41f20b3b22aaf4c9b864e32f20@instructure.com>
Reviewed-by: Andrea Cirulli <b4e55ef5ee4bae8ad31f7c81009bfc0af1714a1f@instructure.com>
QA-Review: James Butters <4c5a489c9bb72d41f20b3b22aaf4c9b864e32f20@instructure.com>
Product-Review: Ahmad Amireh <a53a33601b8dd9d06ae9e50f1f30fbe957aba866@instructure.com>

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