2to3 (in python 3.6.6) will rewrite the reload function to use the imp module. However according to [1] "Deprecated since version 3.4: The imp package is pending deprecation in favor of importlib."
Also running the code with warnings enabled will show a deprecation warning.

Example, take this minimal script:

#!/usr/bin/python
import sys
reload(sys)

Running to 2to3 ends up with:
#!/usr/bin/python
import sys
import imp
imp.reload(sys)

$ PYTHONWARNINGS=d python3 foo.py
test.py:3: DeprecationWarning: the imp module is deprecated in favour of importlib; see the module's documentation for alternative uses
  import imp


[1] https://docs.python.org/3/library/imp.html

Seems this came up when the original version of fixer was added as noted in https://bugs.python.org/issue11797#msg206884 . Looking further this seems to be similar to https://bugs.python.org/issue21446 where it was fixed in 3.7 and master to use importlib.reload . Since 3.6 is having it's last bug fix release I am not sure of the backport. Adding benjamin.peterson to the issue .

It was decided in #21446 to only backport the change, labelled an enhancement, to 3.7 and it is now too late to challenge that decision as 3.6 only gets security fixes.