[1.x] Backport Enable Numpy support for Gluon Block optimize_for to v1.x

ci/docker/install/requirements

@@ -22,7 +22,7 @@ boto3==1.9.229
 cpplint==1.3.0
 Cython==0.29.7
 decorator==4.4.0
-h5py==2.8.0rc1
+h5py<3
 mock==2.0.0
 nose==1.3.7
 nose-timer==0.7.3

ci/docker/install/ubuntu_publish.sh

@@ -81,7 +81,7 @@ apt-get install -y python python-pip python3 python3-pip
 python3 -m pip install --upgrade 'pip<19'
 
 # Restrict numpy version to <1.18 due to use of Python 3.4 on Ubuntu 14.04
-python3 -m pip install --upgrade --ignore-installed nose cpplint==1.3.0 pylint==2.3.1 'numpy>1.16.0,<1.18' nose-timer 'requests<2.19.0,>=2.18.4' h5py==2.8.0rc1 scipy==1.0.1 boto3
+python3 -m pip install --upgrade --ignore-installed nose cpplint==1.3.0 pylint==2.3.1 'numpy>1.16.0,<1.18' nose-timer 'requests<2.19.0,>=2.18.4' 'h5py<3' scipy==1.0.1 boto3
 
 # CMake 3.13.2+ is required
 mkdir /opt/cmake && cd /opt/cmake

python/mxnet/gluon/block.py

@@ -966,6 +966,10 @@ def _build_cache(self, *args):
             # Partition the graph.
             out = out.optimize_for(self._backend, arg_dict, aux_dict, ctx, **self._backend_opts)
 
+            # convert to numpy symbol if needed
+            if _mx_npx.is_np_array():
+                out = out.as_np_ndarray()
+
             #update cached graph with partitioned graph
             self._cached_graph = data, out