Before 4befb30 the detection was broken because we used isinstance
against a LazyObject rather than against a Storage class. That commit
fixed it by looking directly at the object wrapped by LazyObject.
This could however be a problem to anyone who subclasses the
collectstatic management Command and directly supplies a Storage class.
Refs #21581.
Backport of 7e27885c6e from master.
When STATIC_ROOT wasn't set, collectstatic --clear would delete
every files within the current directory and its descendants.
This patch makes the following changes:
Prevent collectstatic from running if STATIC_ROOT isn't set.
Fixed an issue that prevented collectstatic from displaying the
destination directory.
Changed the warning header to notify when the command is run
in dry-run mode.
Backport of 4befb3015c from master
Tim Graham
Loic Bistuer
Aymeric Augustin
Florian Apolloner