merge 8.6: fix and coverage for bug [43c94f95988f3057]: avoid vulnera… #4623

Job	Run time
msvc	10m 52s
gcc	11m 16s
msvc (CHECKS=nodep)	10m 30s
gcc (CFLAGS=-DTCL_NO_DEPRECATED=1)	11m 30s
gcc (--disable-shared)	11m 40s
msvc (OPTS=static)	10m 57s
gcc (--disable-zipfs)	11m 13s
msvc (OPTS=noembed)	10m 28s
gcc (--enable-symbols)	11m 43s
msvc (OPTS=symbols)	10m 33s
msvc (OPTS=symbols STATS=compdbg,memdbg)	15m 31s
gcc (--enable-symbols=mem)	13m 26s
gcc (--enable-symbols=all)	14m 55s
	2h 34m 34s

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