INTERNAL ERROR when there is an non breaking space in a docstring

[Pierre-Sassoulas]

Steps to reproduce the behavior:

1. With the following code:

def plot():
    """ adds a variable to the plot according to it's conf

    >   variables : 
    >       foo:
    >           y: variable(bar)
    >       baz:
    >           color: red

    """

Notice that there is a non breaking space just after variables :.

2. Run Black on it with no argument
3. The following error happens:

INTERNAL ERROR: Black produced code that is not equivalent to the source.  Please report a bug on https://github.com/psf/black/issues.  This diff might be helpful: /tmp/blk_xn6q3h3t.log

--- src
+++ dst
@@ -16,11 +16,11 @@
       body=
         Expr(
           value=
             Constant(
               value=
-                "adds a variable to the plot according to it's conf\n\n>   variables :\xa0\n>       foo:\n>           y: variable(bar)\n>       baz:\n>           color: red",  # str
+                "adds a variable to the plot according to it's conf\n\n>   variables :\n>       foo:\n>           y: variable(bar)\n>       baz:\n>           color: red",  # str
             )  # /Constant
         )  # /Expr
       decorator_list=
       name=
         'plot',  # str

The error disappear by removing the non breaking space.

Environment:

• Version: black-20.8b1
• OS and Python version: Linux/Python 3.8.5
• The bug also happens on master

[Pierre-Sassoulas]

Fixed in eaa337f see #2099 (comment)