Add bug to `gast` dependency so cleanup can be tracked easier.

PiperOrigin-RevId: 270398414

Dockerfile

@@ -56,12 +56,14 @@ RUN mkdir /bazel && \
     rm -f /bazel/installer.sh
 RUN bazel version
 
+# TODO(b/140751117) Unpin gast from 0.2.0.
 # TODO(b/141279425): Remove pinned tf-estimator-nightly version.
 # Install the TensorFlow Federated development environment dependencies
 RUN ${PIP} --no-cache-dir install \
     absl-py~=0.7 \
     attrs~=18.2 \
     cachetools~=3.1.1 \
+    gast==0.2.2 \
     enum34~=1.1 \
     grpcio~=1.22.0 \
     h5py~=2.6 \

requirements.txt

@@ -5,6 +5,7 @@ absl-py~=0.7
 attrs~=18.2
 cachetools~=3.1.1
 enum34~=1.1
+# TODO(b/140751117) Unpin gast from 0.2.0.
 gast==0.2.2
 grpcio~=1.22.0
 h5py~=2.6

tensorflow_federated/tools/development/setup.py

@@ -73,6 +73,8 @@ REQUIRED_PACKAGES = [
     'attrs~=18.2',
     'cachetools~=3.1.1',
     'enum34~=1.1',
+    # TODO(b/140751117) Unpin gast from 0.2.0.
+    'gast==0.2.2',
     'grpcio~=1.22.0',
     'h5py~=2.6',
     'numpy~=1.14',