E TypeError: decode_hex() takes 1 positional argument but 2 were given

[hrishikeshio]

(pye) ~/pyethereum $ pip list
Package          Version  
---------------- ---------
aiohttp          2.3.10   
asn1crypto       0.24.0   
async-lru        0.1.0    
async-timeout    3.0.0    
attrdict         2.0.0    
attrs            18.1.0   
bitcoin          1.1.42   
certifi          2018.4.16
cffi             1.11.5   
chardet          3.0.4    
coincurve        7.1.0    
coverage         4.5.1    
coveralls        1.3.0    
cryptography     2.2.2    
cytoolz          0.9.0.1  
docopt           0.6.2    
eth-abi          1.1.0    
eth-account      0.2.2    
eth-bloom        1.0.0    
eth-hash         0.1.2    
eth-keyfile      0.5.1    
eth-keys         0.2.0b3  
eth-rlp          0.1.2    
eth-tester       0.1.0b21 
eth-utils        1.0.3    
ethereum         2.3.1    
ethereum-serpent 2.0.4    
future           0.16.0   
hexbytes         0.1.0    
idna             2.6      
idna-ssl         1.0.1    
lru-dict         1.1.6    
more-itertools   4.1.0    
multidict        4.3.1    
parsimonious     0.8.0    
pbkdf2           1.3      
pip              10.0.1   
pluggy           0.6.0    
py               1.5.3    
py-ecc           1.4.2    
py-evm           0.2.0a12 
pycparser        2.18     
pycryptodome     3.6.1    
pyethash         0.1.27   
pysha3           1.0.2    
pytest           3.5.1    
pytest-timeout   1.0.0    
PyYAML           3.12     
repoze.lru       0.7      
requests         2.18.4   
rlp              1.0.1    
scrypt           0.8.6    
semantic-version 2.6.0    
setuptools       39.1.0   
six              1.11.0   
toolz            0.9.0    
tox              3.0.0    
trie             1.3.6    
urllib3          1.22     
virtualenv       15.2.0   
vyper            0.0.4    
web3             4.2.1    
websockets       4.0.1    
wheel            0.31.0   
yarl             1.2.4    
(pye) ~/pyethereum $ git show HEAD
commit 3d5ec14032cc471f4dcfc7cc5c947294daf85fe0 (HEAD -> develop, origin/develop, origin/HEAD)
Merge: 7970f94 3339d7e
Author: Joseph Krug <joeykrug@gmail.com>
Date:   Thu May 10 17:14:51 2018 +0700

    Merge pull request #877 from ldct/ldct/fix-rlp-bug
    
    fix block.transaction mutation

(pye) ~/pyethereum $ python -m pytest ethereum/tests/
============================================================================= test session starts ==============================================================================
platform darwin -- Python 3.6.5, pytest-3.5.1, py-1.5.3, pluggy-0.6.0
rootdir: /Users/hrishi/pyethereum, inifile:
plugins: timeout-1.0.0
collected 14847 items / 3 errors                                                                                                                                               

==================================================================================== ERRORS ====================================================================================
_________________________________________________________ ERROR collecting ethereum/tests/hybrid_casper/test_casper.py _________________________________________________________
ethereum/tests/hybrid_casper/test_casper.py:3: in <module>
    from ethereum.hybrid_casper.casper_initiating_transactions import \
ethereum/hybrid_casper/__init__.py:1: in <module>
    from ethereum.hybrid_casper import casper_initiating_transactions, casper_utils, chain, consensus, validator
ethereum/hybrid_casper/casper_initiating_transactions.py:10: in <module>
    viper_rlp_decoder_tx = decode_hex("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", Transaction)  # noqa: E501
E   TypeError: decode_hex() takes 1 positional argument but 2 were given
_________________________________________________________ ERROR collecting ethereum/tests/hybrid_casper/test_chain.py __________________________________________________________
ethereum/tests/hybrid_casper/test_chain.py:5: in <module>
    from ethereum.hybrid_casper import casper_utils
ethereum/hybrid_casper/__init__.py:1: in <module>
    from ethereum.hybrid_casper import casper_initiating_transactions, casper_utils, chain, consensus, validator
ethereum/hybrid_casper/casper_initiating_transactions.py:10: in <module>
    viper_rlp_decoder_tx = decode_hex("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", Transaction)  # noqa: E501
E   TypeError: decode_hex() takes 1 positional argument but 2 were given
_______________________________________________________ ERROR collecting ethereum/tests/hybrid_casper/test_validator.py ________________________________________________________
ethereum/tests/hybrid_casper/test_validator.py:9: in <module>
    from ethereum.hybrid_casper import casper_utils, validator
ethereum/hybrid_casper/__init__.py:1: in <module>
    from ethereum.hybrid_casper import casper_initiating_transactions, casper_utils, chain, consensus, validator
ethereum/hybrid_casper/casper_initiating_transactions.py:10: in <module>
    viper_rlp_decoder_tx = decode_hex("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", Transaction)  # noqa: E501
E   TypeError: decode_hex() takes 1 positional argument but 2 were given
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Interrupted: 3 errors during collection !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
=========================================================================== 3 error in 7.66 seconds ============================================================================
(pye) ~/pyethereum $