Fix bug causing kitty protocol escape sequences to break multiline (#863)

Reproducer (must be run in kitty or another terminal with support for
kitty's escape sequences[*]):
  $ PS1=$'\E[4:5m→\E[0m '
  → <Enter a command prompt spanning multiple lines>
  → <Home> + <End>

The bottom line shifts over two characters more than it ought. This is
because the ':' in the escape sequence causes ksh to calculate the
wrong length for the sequence.

- Continue calculating the length of the escape sequence after
  encountering a ':' in the sequence.

[*]: https://sw.kovidgoyal.net/kitty/underlines/

Author: JohnoKing

NEWS

@@ -2,12 +2,18 @@ This documents significant changes in the dev branch of ksh 93u+m.
 For full details, see the git log at: https://github.com/ksh93/ksh
 Uppercase BUG_* IDs are shell bug IDs as used by the Modernish shell library.
 
-2025-07-30:
+2025-05-31:
+
+- Fixed a bug that caused the multiline option to break when PS*
+  prompts use the kitty terminal's escape sequence (e.g. $'\E[4:4m'
+  in the PS1 prompt for formatting spaced dots).
+
+2025-05-30:
 
 - The editor typeahead buffer and the limit for the ${.sh.edchar} variable
   (used with the KEYBD trap) has been increased from 80 to 500 bytes.
 
-2025-07-29:
+2025-05-29:
 
 - Fixed a serious but rarely occurring regression that corrupts variable
   names in assignments. It could be triggered in large scripts and cause a

src/cmd/ksh93/edit/edit.c

@@ -420,7 +420,7 @@ void	ed_setup(Edit_t *ep, int fd, int reedit)
 						skip = 0;
 						continue;
 					}
-					if(n==3 && (c=='?' || c=='!'))
+					if(n==3 && (c=='?' || c=='!' || c==':'))
 						continue;
 					else if(n>1 && c==';')
 						skip = 1;

src/cmd/ksh93/include/version.h

@@ -18,7 +18,7 @@
 #include <ast_release.h>
 #include "git.h"
 
-#define SH_RELEASE_DATE	"2025-05-30"	/* must be in this format for $((.sh.version)) */
+#define SH_RELEASE_DATE	"2025-05-31"	/* must be in this format for $((.sh.version)) */
 /*
  * This comment keeps SH_RELEASE_DATE a few lines away from SH_RELEASE_SVER to avoid
  * merge conflicts when cherry-picking dev branch commits onto a release branch.