I caught the following snippet at the end of my /var/log/bsdinstall_log:

===
DEBUG: Running installation step: services
local: Not in a function
/usr/libexec/bsdinstall/services: cannot create  : Read-only file system
/usr/libexec/bsdinstall/services: /tmp/bsdinstall/etc/rc.conf.services: \
 Permission denied
===
The `local: Not in a function' is obvious, and was introduced by myself in
SVN revision 256348.

The latter two are caused by the attempt to use "\" to continue the line
after using the ">>" redirect. This appears to attempt to write a file with
the name " " in the current directory and subsequently attempts to execute
the file that was originally intended for writing (which is not executable;
hence the `Permission denied'). That was introduced in SVN r228192 about
2 years ago, apparently unnoticed until I started going over the debug
outputs very carefully.

MFC after:	3 days

usr.sbin/bsdinstall/scripts/services

@@ -50,13 +50,12 @@ DAEMONS=$(dialog --backtitle "FreeBSD Installer" \
 2>&1 1>&3)
 exec 3>&-
 
-local havedump=
+havedump=
 for daemon in $DAEMONS; do
 	if [ "$daemon" == "dumpdev" ]; then
 		havedump=1
-		echo \# Set dumpdev to \"AUTO\" to enable crash dumps, \
-			\"NO\" to disable >> \ 
-			$BSDINSTALL_TMPETC/rc.conf.services
+		echo '# Set dumpdev to "AUTO" to enable crash dumps, "NO"' \
+		     'to disable' >> $BSDINSTALL_TMPETC/rc.conf.services
 		echo dumpdev=\"AUTO\" >> $BSDINSTALL_TMPETC/rc.conf.services
 		continue
 	fi