bug#21671: [PATCH] fix python.el hanging up during fontification #21657

[immerrr again]

Two patches are included.

One fixes the fact that for some reason syntax-propertize--done has
ceased to be buffer-local after commit [1] and for some reason commit
[2] did not help. I did it the way other buffer-local variables are
initialized and it worked. The change fixes #21657 that was failing
because syntax-propertize--done was inherited from scratch buffer and
docstring boundaries were not propertized as a result.

The other infinite loop I found accidentally when adding a whitespace
before module docstring. I have fixed one corner-case of it, but in
other circumstances I'd argue that whatever smart extensions
python-mode adds to forward-sexp, those extensions should never move
point less than the normal forward-sexp should.

Cheers,
immerrr

1. 
https://github.com/emacs-mirror/emacs/commit/3928ef2dd5b8febf3b1d9c1bfb22af3698d16bea

2. 
https://github.com/emacs-mirror/emacs/commit/0360b7f2c4f0358106e229de4dfe91a67445a50c

0002-Prevent-infinite-loop-in-python-info-docstring-p.patch
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0001-Fix-syntax-propertize-done-to-be-buffer-local.patch
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