Python 3.6.9 (Colab) doesn't handle circular imports properly

[zphang]

We primarily develop against Python 3.7, but Colab uses 3.6.9, which handles circular imports a little differently.

This currently causes problem with our jiant.tasks imports. We run into the following issue with 3.6.9 (as one example)

1. jiant.tasks: from .retrieval import *
2. jiant.retrieval:

• from jiant.tasks.lib.glue_diagnostics import GlueDiagnosticsTask
• from jiant.tasks.lib.mnli import MnliTask

3. jiant.tasks.lib.glue_diagnostics: import jiant.tasks.lib.mnli as mnli

This causes Python 3.6.9 to fail to import tasks.

I am pushing a temporary fix to convert all derivative tasks to do a relative import (#150)

• jiant.tasks.lib.glue_diagnostics
• jiant.tasks.lib.mnli_mismatched
• jiant.tasks.lib.superglue_axg
• jiant.tasks.lib.superglue_axb

while we pursue a longer term solution.

[zphang]

Colab has apparently updated to 3.7, so moving forward this should no longer be an issue.