Make tf-nightly pip depend on tf-estimator-nightly pip.

PiperOrigin-RevId: 221708873

tensorflow/tools/pip_package/setup.py

@@ -87,7 +87,8 @@ if 'tf_nightly' in project_name:
   for i, pkg in enumerate(REQUIRED_PACKAGES):
     if 'tensorboard' in pkg:
       REQUIRED_PACKAGES[i] = 'tb-nightly >= 1.13.0a0, < 1.14.0a0'
-      break
+    if 'tensorflow_estimator' in pkg:
+      REQUIRED_PACKAGES[i] = 'tf-estimator-nightly'
 
 # weakref.finalize and enum were introduced in Python 3.4
 if sys.version_info < (3, 4):