Reporting syntax error when check which version is compatible with other requirements using pip

[lj564]

Description

pip install tensor2tensor==1.13.4 All packages were downloaded well. But it report errors because of syntax error of promise-0.2.2's byteplay.

INFO : pip is looking at multiple versions of promise to determine which version is compatible with other requirements. This could take a while.

Environment information

OS: Ubuntu Server 18.04.5 LTS python 3.7.0

For bugs: reproduction and error logs

ERROR: Command errored out with exit status 1: command: /home/luojuan/.pyenv/versions/3.7.0/envs/uda/bin/python3.7 -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'/tmp/pip-install-3lt079gq/promise_edc84b4b1b914f5f9a25a1c8fc51eb2f/setup.py'"'"'; file='"'"'/tmp/pip-install-3lt079gq/promise_edc84b4b1b914f5f9a25a1c8fc51eb2f/setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(file);code=f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, file, '"'"'exec'"'"'))' egg_info --egg-base /tmp/pip-pip-egg-info-rd664yo3 cwd: /tmp/pip-install-3lt079gq/promise_edc84b4b1b914f5f9a25a1c8fc51eb2f/ Complete output (10 lines): Traceback (most recent call last): File "", line 1, in File "/tmp/pip-install-3lt079gq/promise_edc84b4b1b914f5f9a25a1c8fc51eb2f/setup.py", line 4, in import promise File "/tmp/pip-install-3lt079gq/promise_edc84b4b1b914f5f9a25a1c8fc51eb2f/promise/init.py", line 68, in from promise.byteplay import * File "/tmp/pip-install-3lt079gq/promise_edc84b4b1b914f5f9a25a1c8fc51eb2f/promise/byteplay.py", line 181 raise ValueError, "Opcode stack behaviour depends on arg" ^ SyntaxError: invalid syntax ---------------------------------------- ERROR: Command errored out with exit status 1: python setup.py egg_info Check the logs for full command output.

I tried to download promise-0.2.2.tar.gz and modified byteplay.py but it did'nt work. I tried to change tensor2tensor‘s version and it did work. But I don't know why.