allow repeated extra arguments (#1673)

Co-authored-by: Martin Durant <[email protected]>

fsspec/core.py

@@ -346,7 +346,10 @@ def _un_chain(path, kwargs):
         kws = kwargs.pop(protocol, {})
         if bit is bits[0]:
             kws.update(kwargs)
-        kw = dict(**extra_kwargs, **kws)
+        kw = dict(
+            **{k: v for k, v in extra_kwargs.items() if k not in kws or v != kws[k]},
+            **kws,
+        )
         bit = cls._strip_protocol(bit)
         if (
             protocol in {"blockcache", "filecache", "simplecache"}

fsspec/tests/test_core.py

@@ -465,3 +465,21 @@ def test_chained_url(ftp_writable):
 def test_automkdir_local():
     fs, _ = fsspec.core.url_to_fs("file://", auto_mkdir=True)
     assert fs.auto_mkdir is True
+
+
+def test_repeated_argument():
+    pytest.importorskip("adlfs")
+    from fsspec.core import url_to_fs
+
+    fs, url = url_to_fs(
+        "az://[email protected]/DATA",
+        anon=False,
+        account_name="ACCOUNT",
+    )
+    assert fs.storage_options == {"account_name": "ACCOUNT", "anon": False}
+    with pytest.raises(TypeError):
+        url_to_fs(
+            "az://[email protected]/DATA",
+            anon=False,
+            account_name="OTHER",
+        )