Fix error in special bltin disabling .sh.tilde disc (re: 3c2b0dc)

Since sh_exit() in fault.c now sets sh.tilde_block to 0, an error
in a special built-in will set that to 0. Then the tilde expansion
completes and sh.tilde_block is decreased in tilde_expand2().
Meaning it gets decreased after being set to 0, so it gets
permanently blocked due to its value -1.

The simplest fix is to explicitly set sh.tilde_block to 1 and 0
instead of increasing and decreasing it.

src/cmd/ksh93/include/version.h

@@ -18,7 +18,7 @@
 
 #define SH_RELEASE_FORK	"93u+m"		/* only change if you develop a new ksh93 fork */
 #define SH_RELEASE_SVER	"1.1.0-alpha"	/* semantic version number: https://semver.org */
-#define SH_RELEASE_DATE	"2023-09-16"	/* must be in this format for $((.sh.version)) */
+#define SH_RELEASE_DATE	"2023-09-24"	/* must be in this format for $((.sh.version)) */
 #define SH_RELEASE_CPYR	"(c) 2020-2023 Contributors to ksh " SH_RELEASE_FORK
 
 /* Scripts sometimes field-split ${.sh.version}, so don't change amount of whitespace. */

src/cmd/ksh93/sh/macro.c

@@ -2717,10 +2717,10 @@ static void tilde_expand2(int offset)
 	if(!sh.tilde_block && SH_TILDENOD->nvfun && SH_TILDENOD->nvfun->disc)
 	{
 		stkfreeze(sh.stk,1);			/* terminate current stack object to avoid data corruption */
-		sh.tilde_block++;
+		sh.tilde_block = 1;
 		nv_putval(SH_TILDENOD, &stakp[offset], 0);
 		cp = nv_getval(SH_TILDENOD);
-		sh.tilde_block--;
+		sh.tilde_block = 0;
 		if(cp[0]=='\0' || cp[0]=='~')
 			cp = NULL;			/* do not use empty or unexpanded result */
 		stkset(sh.stk,stakp,curoff);		/* restore stack to state on function entry */

src/cmd/ksh93/tests/tilde.sh

@@ -165,5 +165,22 @@ do	(
 	fi
 done
 
+# ======
+
+got=$(
+	.sh.tilde.get()
+	{
+		case ${.sh.tilde} in
+		"~ksh") .sh.value=/usr/local/src/ksh93/ksh ;;
+		"~ers") trap -Q; .sh.value=BAD ;;	#test
+		esac
+	}
+	{ : ~ers; } 2>/dev/null
+	echo ~ksh
+)
+exp=/usr/local/src/ksh93/ksh
+[[ $got == "$exp" ]] || err_exit "error in special builtin disables .sh.tilde discipline" \
+	"(expected $(printf %q "$exp"), got $(printf %q "$got"))"
+
 # ======
 exit $((Errors<125?Errors:125))