[Misc] add requests as the package dependency (#1268)

conda/dgl/meta.yaml

@@ -18,6 +18,7 @@ requirements:
     - numpy
     - scipy
     - networkx
+    - requests
 
 build:
   script_env:

python/dgl/data/utils.py

@@ -9,16 +9,10 @@ import zipfile
 import tarfile
 import numpy as np
 import warnings
+import requests
 
 from .graph_serialize import save_graphs, load_graphs, load_labels
 
-try:
-    import requests
-except ImportError:
-    class requests_failed_to_import(object):
-        pass
-    requests = requests_failed_to_import
-
 __all__ = ['loadtxt','download', 'check_sha1', 'extract_archive',
            'get_download_dir', 'Subset', 'split_dataset',
            'save_graphs', "load_graphs", "load_labels"]

python/setup.py

@@ -121,6 +121,7 @@ setup(
         'numpy>=1.14.0',
         'scipy>=1.1.0',
         'networkx>=2.1',
+        'requests>=2.19.0',
     ],
     url='https://github.com/dmlc/dgl',
     distclass=BinaryDistribution,