workaround for pathlib on py 3.7

fixes #534

pathlib._NormalAccessor wraps `open` in `staticmethod` for py < 3.7 but
not 3.7. That means we `Path.open` calls `green.os.open` with `file`
being a pathlib._NormalAccessor object, and the other arguments shifted.
Fortunately pathlib doesn't use the `dir_fd` argument, so we have space
in the parameter list. We use some heuristics to detect this and adjust
the parameters (without importing pathlib)

1 files changed, 11 insertions, 0 deletions

diff --git a/tests/os_test.py b/tests/os_test.py
new file mode 100644
index 0000000..3688d19
--- /dev/null
+++ b/tests/os_test.py
@@ -0,0 +1,11 @@
+import eventlet
+import six
+
+
+if six.PY3:
+    def test_pathlib_open_issue_534():
+        pathlib = eventlet.import_patched('pathlib')
+        path = pathlib.Path(__file__)
+        with path.open():
+            # should not raise
+            pass