Error during 2to3 conversion

[krow4869]

So I wanted to convert bk-chem-0.13.0 source code from Python 2 to Python 3 using 2to3. So in cmd, I ran this command so that it will convert all the files in the directory:

2to3 C:\User\Admin\Downloads\bkchem\. -w

So far, so good: here's some output dump sample from just before the error:

Output:
RefactoringTool: Refactored C:\Users\Admin\Downloads\bkchem\.\bkchem\plugins\piddle\PixMapWrapper.py
--- C:\Users\Admin\Downloads\bkchem\.\bkchem\plugins\piddle\PixMapWrapper.py    (original)
+++ C:\Users\Admin\Downloads\bkchem\.\bkchem\plugins\piddle\PixMapWrapper.py    (refactored)
@@ -109,7 +109,7 @@
                elif attr == 'hRes' or attr == 'vRes':
                        # 16.16 fixed format, so just shift 16 bits
                        self._stuff(attr, int(val) << 16)
-               elif attr in _pmElemFormat.keys():
+               elif attr in list(_pmElemFormat.keys()):
                        # any other pm attribute -- just stuff
                        self._stuff(attr, val)
                else:
@@ -129,7 +129,7 @@
                elif attr == 'hRes' or attr == 'vRes':
                        # 16.16 fixed format, so just shift 16 bits
                        return self._unstuff(attr) >> 16
-               elif attr in _pmElemFormat.keys():
+               elif attr in list(_pmElemFormat.keys()):
                        # any other pm attribute -- just unstuff
                        return self._unstuff(attr)
                else:
@@ -151,7 +151,7 @@
                if y2 == None:
                        dest[3] = y1 + src[3]-src[1]
                if not port: port = Qd.GetPort()
-               print "blit port:", port
+               print("blit port:", port)
                Qd.CopyBits(self.PixMap(), port.portBits, src, tuple(dest),
                                QuickDraw.srcCopy, None)

And here, the error comes:

Error:
Traceback (most recent call last):
  File "c:\users\admin\appdata\local\programs\python\python37\lib\runpy.py", line 193, in _run_module_as_main
    "__main__", mod_spec)
  File "c:\users\admin\appdata\local\programs\python\python37\lib\runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "C:\Users\Admin\AppData\Local\Programs\Python\Python37\Scripts\2to3.exe\__main__.py", line 9, in <module>
  File "c:\users\admin\appdata\local\programs\python\python37\lib\site-packages\cmd_2to3\__main__.py", line 6, in main
    sys.exit(l2to3_main("lib2to3.fixes"))
  File "c:\users\admin\appdata\local\programs\python\python37\lib\lib2to3\main.py", line 259, in main
    options.processes)
  File "c:\users\admin\appdata\local\programs\python\python37\lib\lib2to3\refactor.py", line 687, in refactor
    items, write, doctests_only)
  File "c:\users\admin\appdata\local\programs\python\python37\lib\lib2to3\refactor.py", line 280, in refactor
    self.refactor_dir(dir_or_file, write, doctests_only)
  File "c:\users\admin\appdata\local\programs\python\python37\lib\lib2to3\refactor.py", line 300, in refactor_dir
    self.refactor_file(fullname, write, doctests_only)
  File "c:\users\admin\appdata\local\programs\python\python37\lib\lib2to3\refactor.py", line 728, in refactor_file
    *args, **kwargs)
  File "c:\users\admin\appdata\local\programs\python\python37\lib\lib2to3\refactor.py", line 322, in refactor_file
    input, encoding = self._read_python_source(filename)
  File "c:\users\admin\appdata\local\programs\python\python37\lib\lib2to3\refactor.py", line 318, in _read_python_source
    return f.read(), encoding
  File "c:\users\admin\appdata\local\programs\python\python37\lib\codecs.py", line 322, in decode
    (result, consumed) = self._buffer_decode(data, self.errors, final)
UnicodeDecodeError: 'utf-8' codec can't decode byte 0x92 in position 18708: invalid start byte

Based on my understanding, I think that the error is not with the bkchem code (since there was no mention of it in the traceback), but with 2to3. What's happening and how to fix it?

[Larz60+]

show code from line 322 (add lines before and after to show context)

[krow4869]

show code from line 322 (add lines before and after to show context)

Code from codecs.py (lines 319-325):

def decode(self, input, final=False):
        # decode input (taking the buffer into account)
        data = self.buffer + input
        (result, consumed) = self._buffer_decode(data, self.errors, final)
        # keep undecoded input until the next call
        self.buffer = data[consumed:]
        return result

[Larz60+]

I think you need encoding='windows-1252', but this apparently would be in self._buffer_decode()