I think the OP might actually want to replace literal or entity nbspaces
with regular spaces. There certainly may be reasonable reasons to want to
do that.
I think that the OP might be helped by a prefilter written in python. The
following tries to skip any fenced code or code blocks in order to not
replace nbsp entities inside code. It may be thrown by things like
`\~~~strikeout~~` but those are unlikely in practice.

````python
import sys
import re

inp = sys.stdin.read()
txt = inp.decode('utf-8')
pat = u"""(?isxu)
# Match delimited code or code block
(?P<code>
(?P<backtick> \`{1,} ) .*? (?P=backtick)
|
(?P<tilde> \~{3,} ) .*?  (?P=tilde)
)
|
# Match any form of nbsp
( \& (?: nbsp|[#]160|[#]xa0) \; | \u00a0 )
"""

# keep code and replace ordinary space
def rep(m):
    return m.group(1) if m.group(1) else u"\u0020"

print re.sub(pat, rep, txt).encode('utf-8')
````

fre 4 aug. 2017 kl. 00:30 skrev Kolen Cheung <christian.kolen-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>:

> I actually want to know why you would want to remove that in the first
> place? It seems only if the source has bugs you would want to do that.
>
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