[fix][Pipe] fallback for Pipe tests on internal pytorch numbering (#216)

* fallback on internal pytorch numbering

tests/nn/pipe_process/test_pipe.py

@@ -375,6 +375,18 @@ def checkpoint_eval(pipeline_style):
 
 def torch_version() -> Tuple[int, ...]:
     result = version.parse(torch.__version__).release
+
+    # Catch torch version if run against internal pre-releases, like `1.8.0a0fb`,
+    # for which version.parse().release will return None (version becomes of LegacyVersion type)
+    if result is None:
+        # Two options here:
+        # - either skip this version,
+        # - or check that Pipe is not broken by this ongoing development.
+
+        # Assuming that we're interested in the second usecase more than the first,
+        # return the pre-release or dev numbering
+        numbering = torch.__version__.split(".")
+        result = (int(numbering[0]), int(numbering[1]), 0)
     assert result
     return result