#2420 unexpected stack trace in "unknown"

[Vince Darley]

This script illustrates the problem:

set auto_index(foo) [list proc foo {args} { return -code
1 "cancel" }]
set blah [string repeat "\u2022abcdefg " 20]
foo $blah

The problem arises because unknown makes a string
comparison using 'string length', whereas the core code,
it seems uses the first 160 bytes rather than chars of
the string.

If we remove the '\u2022' unicode sequence from 'blah',
then all is ok.

[Vince Darley]

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Searching for '150' in tcl/generic shows a number of places
where there may be problems. It wouldn't surprise me if multi-
byte characters are even split into pieces by the core code.

[Don Porter]

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this appears to be a duplicate
of Bug 760872.

And has nothing to do with TIP 90.

[Vince Darley]

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Ok -- thanks. Looking more closely at the code it is clearly
only coincidence that I've just seen the bug since tip90, since
it has always been there.