> Hm, but there the old parser seems at fault: it points to the last space rather than beyond it?

Both parsers seem to have the same behaviour, when parsing files. I just found out that even the new parser points to the `|` if there is not trailing whitespace:

╰─ cat -e t.py
x = 1 | 2 |$
╰─ ./python.exe t.py
  File "/Users/lysnikolaou/Repositories/cpython/t.py", line 1
    x = 1 | 2 |
              ^
SyntaxError: invalid syntax
╰─ ./python.exe -X oldparser t.py
  File "/Users/lysnikolaou/Repositories/cpython/t.py", line 1
    x = 1 | 2 |
              ^
SyntaxError: invalid syntax

I'll investigate more tomorrow.