edit.c: get_tput(): also deactivate DEBUG trap (re: 667034f)

Reproducer:
1. Invoke xterm (effects vary by terminal)
2. Create issue828.sh with:
   trap 'printf "\033]0;%s\007" "${.sh.command}" >&2' DEBUG
3. ENV=$PWD/issue828.sh ksh

Expected behaviour: graceful init, titlebar updated before
executing each command. Actual behaviour: audible beep and messed
up terminal display on init, followed by expected behaviour.

Analysis: The get_tput command introduced in the referenced commit
invokes tput(1) to obtain escape sequences needed for multiline
editing. To avoid noise it deactivates the xtrace and verbose shell
options, but I had not thought of also deactivating the DEBUG trap.
Since this gets run after reading the ENV script, the DEBUG trap is
executed for the .sh.value assignment, which echoes those escape
sequences to the terminal.

src/cmd/ksh93/edit/edit.c: get_tput():
- Temporarily deactivate the DEBUG trap while getting the shell to
  run the command substitution that invokes tput(1).

Thanks to Nick Papadonis (@nickpapadonis) for the report.
Resolves: #828

Author: McDutchie

NEWS

@@ -7,6 +7,10 @@ Uppercase BUG_* IDs are shell bug IDs as used by the Modernish shell library.
 - Fixed: 'stty -echo' failed to turn off echoing of terminal input in
   scripts for subsequent 'read' commands. Bug introduced on 2021-02-11.
 
+- Fixed an issue where any DEBUG trap defined in .kshrc (or other $ENV script)
+  was unexpectedly executed for internal 'tput' commands that ksh invokes at
+  init (to obtain terminal escape sequences for multiline editing).
+
 2025-03-28:
 
 - Fixed crash upon resizing the terminal window after 'stty -echo', including

src/cmd/ksh93/edit/edit.c

@@ -296,11 +296,13 @@ void ed_ringbell(void)
 static void get_tput(char *tp, char **cpp)
 {
 	Shopt_t	o = sh.options;
+	char	*d = sh.st.trap[SH_DEBUGTRAP];
 	char	*cp;
 	sigblock(SIGINT);
 	sh_offoption(SH_RESTRICTED);
 	sh_offoption(SH_VERBOSE);
 	sh_offoption(SH_XTRACE);
+	sh.st.trap[SH_DEBUGTRAP] = NULL;
 	sfprintf(sh.strbuf,".sh.value=${ \\command -p tput %s 2>/dev/null;}",tp);
 	sh_trap(sfstruse(sh.strbuf),0);
 	if((cp = nv_getval(SH_VALNOD)) && (!*cpp || strcmp(cp,*cpp)!=0))
@@ -316,6 +318,7 @@ static void get_tput(char *tp, char **cpp)
 		*cpp = NULL;
 	}
 	nv_unset(SH_VALNOD);
+	sh.st.trap[SH_DEBUGTRAP] = d;
 	sh.options = o;
 	sigrelease(SIGINT);
 }