bug#23443: 25.0.93; Temporary change to syntax-table is in effect during syntax-propertize

[Andreas Röhler]

reopen 23443

The proposed solution, which has to bind syntax-propertize-function to 
nil before calling scan-sexp, reads like a work around. These things 
shouldn't be necessary.

Assume a fix must affect usage of syntax-propertize-function and probably is 
not a trivial one.
Its design seems worth further discussion.

For example reading:

"The specified function may call ‘syntax-ppss’ on any position
before END, but it should not call ‘syntax-ppss-flush-cache’,
which means that it should not call ‘syntax-ppss’ on some
position and later modify the buffer on some earlier position."