This restores the earlier behavior of the first positional argument to
terraform init in 0.9, but as a command line option.
The positional argument was removed to improve consistency with other
commands that take a working directory as their first positional argument.
It was originally intended that this functionality would return in a
later release along with some other general improvements to Terraform's
module handling, but we're introducing here an interim solution that
uses the existing module source concept, to allow for easier porting of
workflows that previously depended on the automatic copy behavior.
In a future release this feature may change again as the module
improvements design firms up, but we expect it to be broadly compatible
with this temporary state.
8a7a0a7459