Enable tmux to expand special format codes like '#S' inside of shell command special sequences. E.g. let something like `#(echo #S)` work.

preexpand.diff

diff --git a/status.c b/status.c
index deb1b60..175623d 100644
--- a/status.c
+++ b/status.c
@@ -38,7 +38,7 @@ void	status_job_free(void *);
 void	status_job_callback(struct job *);
 char   *status_print(
 	    struct client *, struct winlink *, time_t, struct grid_cell *);
-void	status_replace1(struct client *, char **, char **, char *, size_t, int);
+void	status_replace1(struct client *, struct format_tree *, char **, char **, char *, size_t, int);
 void	status_message_callback(int, short, void *);
 
 const char *status_prompt_up_history(u_int *);
@@ -360,13 +360,15 @@ out:
 
 /* Replace a single special sequence (prefixed by #). */
 void
-status_replace1(struct client *c, char **iptr, char **optr, char *out,
+status_replace1(struct client *c, struct format_tree *ft, char **iptr, char **optr, char *out,
     size_t outsize, int jobsflag)
 {
 	char	ch, tmp[256], *ptr, *endptr;
 	size_t	ptrlen;
 	long	limit;
+	int     lastesc;
 
+    lastesc = 0;
 	errno = 0;
 	limit = strtol(*iptr, &endptr, 10);
 	if ((limit == 0 && errno != EINVAL) ||
@@ -383,8 +385,38 @@ status_replace1(struct client *c, char **iptr, char **optr, char *out,
 			ch = ')';
 			goto skip_to;
 		}
-		if ((ptr = status_find_job(c, iptr)) == NULL)
+		/*
+		 * Before running the job, replace any special squences within it
+		 * To do so, first search for closing brace:
+		 */
+		endptr = *iptr;
+		for (; *endptr != '\0'; endptr++) {
+			if (!lastesc && *endptr == ')') {
+				break;		/* unescaped ) is the end */
+			}
+			if (!lastesc && *endptr == '\\') {
+				lastesc = 1;
+				continue;	/* skip \ if not escaped */
+			}
+			lastesc = 0;
+		}
+
+		/* Now that we have the end of this special sequence, zero it out */
+		*endptr = '\0';
+
+		/* We now use format_expand to do the expansion pass over iptr */
+		ptr = format_expand(ft, *iptr);
+		sprintf(tmp, "%s)", ptr);
+		free(ptr);
+
+		/* We finally restore the closing parenthesis, and run the job */
+		//*endptr = ')';
+		ptr = &tmp[0];
+		log_debug("Launching job: %s", ptr);
+		if ((ptr = status_find_job(c, &ptr)) == NULL)
 			return;
+		*iptr = endptr;
+		log_debug("Result: %s", ptr);
 		goto do_replace;
 	case '[':
 		/*
@@ -455,6 +487,16 @@ status_replace(struct client *c, struct session *s, struct winlink *wl,
 	iptr = in;
 	optr = out;
 
+	ft = format_create();
+	if (c != NULL)
+		format_client(ft, c);
+	if (s != NULL)
+		format_session(ft, s);
+	if (s != NULL && wl != NULL)
+		format_winlink(ft, s, wl);
+	if (wp != NULL)
+		format_window_pane(ft, wp);
+
 	while (*iptr != '\0') {
 		if (optr >= out + (sizeof out) - 1)
 			break;
@@ -464,19 +506,10 @@ status_replace(struct client *c, struct session *s, struct winlink *wl,
 			*optr++ = ch;
 			continue;
 		}
-		status_replace1(c, &iptr, &optr, out, sizeof out, jobsflag);
+		status_replace1(c, ft, &iptr, &optr, out, sizeof out, jobsflag);
 	}
 	*optr = '\0';
 
-	ft = format_create();
-	if (c != NULL)
-		format_client(ft, c);
-	if (s != NULL)
-		format_session(ft, s);
-	if (s != NULL && wl != NULL)
-		format_winlink(ft, s, wl);
-	if (wp != NULL)
-		format_window_pane(ft, wp);
 	expanded = format_expand(ft, out);
 	format_free(ft);
 	return (expanded);
@@ -529,7 +562,7 @@ status_find_job(struct client *c, char **iptr)
 
 	/* If not found at all, start the job and add to the tree. */
 	if (so == NULL) {
-		job_run(cmd, NULL, status_job_callback, status_job_free, c);
+		job_run(cmd, c->session, status_job_callback, status_job_free, c);
 		c->references++;
 
 		so = xmalloc(sizeof *so);