Ignore modified uncle test that seems broken

See the code comment for the github issue.

Author: carver

tests/json-fixtures/test_blockchain.py

@@ -181,12 +181,18 @@
     ('GeneralStateTests/stSStoreTest/InitCollision.json', 'InitCollision_d0g0v0_Istanbul'),  # noqa: E501
     # Perhaps even stranger, d2 starts failing again after fixing a long-hidden consensus bug
     # but not in Constantinople, only in Istanbul.
-    ('GeneralStateTests/stSStoreTest/InitCollision.json', 'InitCollision_d2g0v0_Istanbul'),  # noqa: E501
-    ('GeneralStateTests/stSStoreTest/InitCollision.json', 'InitCollision_d1g0v0_Istanbul'),  # noqa: E501
+    ('GeneralStateTests/stSStoreTest/InitCollision.json', 'InitCollision_d2g0v0_Istanbul'),
+    ('GeneralStateTests/stSStoreTest/InitCollision.json', 'InitCollision_d1g0v0_Istanbul'),
     # The d2 variant started failing again after fixing a long-hidden consensus bug
     # but only in Istanbul, not in Constantinople.
-    ('GeneralStateTests/stSStoreTest/InitCollision.json', 'InitCollision_d2g0v0_Istanbul'),  # noqa: E501
-    ('GeneralStateTests/stSStoreTest/InitCollision.json', 'InitCollision_d3g0v0_Istanbul'),  # noqa: E501
+    ('GeneralStateTests/stSStoreTest/InitCollision.json', 'InitCollision_d2g0v0_Istanbul'),
+    ('GeneralStateTests/stSStoreTest/InitCollision.json', 'InitCollision_d3g0v0_Istanbul'),
+    # It's not clear how or why this test changed. It doesn't make sense that it only tests Istanbul
+    # either. See: https://github.com/ethereum/tests/issues/787
+    # The test seems to claim to test what happens if the uncle timestamp is the same as
+    # the block, but the RLP doesn't encode a matching timestamp.
+    ('InvalidBlocks/bcUncleHeaderValidity/incorrectUncleTimestamp.json', 'incorrectUncleTimestamp_Istanbul'),  # noqa: E501
+    ('InvalidBlocks/bcUncleHeaderValidity/incorrectUncleTimestamp.json', 'incorrectUncleTimestamp_Berlin'),  # noqa: E501
 }