open('docs/introduction.rst').read()) and UnicodeDecodeError: 'charmap' codec can't decode byte 0x81 in position 10312: character maps to <undefined>

[bsekiewicz]

When I try to install a package from GitHub, it gives me an error:

ERROR: Command errored out with exit status 1:
     command: 'D:\apps\Anaconda3\envs\autospider\python.exe' -c 'import sys, setuptools, tok
enize; sys.argv[0] = '"'"'C:\\Users\\AppData\\Local\\Temp\\pip-req-build-mvfy06ye\\se
tup.py'"'"'; __file__='"'"'C:\\Users\\AppData\\Local\\Temp\\pip-req-build-mvfy06ye\\s
etup.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 'C:\Users\barto\AppData\Local\Temp\pip-pip-egg-info-i5jufi9v'
         cwd: C:\Users\barto\AppData\Local\Temp\pip-req-build-mvfy06ye\
    Complete output (7 lines):
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
      File "C:\Users\AppData\Local\Temp\pip-req-build-mvfy06ye\setup.py", line 6, in <
module>
        introduction = re.sub(r':members:.+|..\sautomodule::.+|:class:|:func:|:ref:', '', op
en('docs/introduction.rst').read())
      File "\apps\Anaconda3\envs\lib\encodings\cp1250.py", line 23, in decode
        return codecs.charmap_decode(input,self.errors,decoding_table)[0]
    UnicodeDecodeError: 'charmap' codec can't decode byte 0x81 in position 10312: character
maps to <undefined>

The problem is with introduction.rst file. Changing open('docs/introduction.rst').read()) in my fork repo into open('docs/introduction.rst', encoding='utf-8').read()) in setup.py solved problem.