patch 8.2.1545: ch_logfile() is unclear about closing when forking

Problem:    ch_logfile() is unclear about closing when forking.
Solution:   Adjust the log messages.

src/channel.c

@@ -144,6 +144,7 @@ fd_close(sock_T fd)
 
 // Log file opened with ch_logfile().
 static FILE *log_fd = NULL;
+static char_u *log_name = NULL;
 #ifdef FEAT_RELTIME
 static proftime_T log_start;
 #endif
@@ -158,7 +159,7 @@ ch_logfile(char_u *fname, char_u *opt)
 	if (*fname != NUL)
 	    ch_log(NULL, "closing this logfile, opening %s", fname);
 	else
-	    ch_log(NULL, "closing logfile");
+	    ch_log(NULL, "closing logfile %s", log_name);
 	fclose(log_fd);
     }
 
@@ -170,6 +171,8 @@ ch_logfile(char_u *fname, char_u *opt)
 	    semsg(_(e_notopen), fname);
 	    return;
 	}
+	vim_free(log_name);
+	log_name = vim_strsave(fname);
     }
     log_fd = file;
 

src/os_unix.c

@@ -4683,8 +4683,10 @@ mch_call_shell_fork(
 
 # ifdef FEAT_JOB_CHANNEL
 	    if (ch_log_active())
-		// close the log file in the child
+	    {
+		ch_log(NULL, "closing channel log in the child process");
 		ch_logfile((char_u *)"", (char_u *)"");
+	    }
 # endif
 
 	    if (!show_shell_mess || (options & SHELL_EXPAND))

src/version.c

@@ -754,6 +754,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1545,
 /**/
     1544,
 /**/