run-session: fix evaluation of $cmd variable (MR 16)

* Drop extraneous $cmd variable reevaluation
* Update the comment for this feature. The session profile is evaluated
  only later in the script, so the environment variable should be set
  in the regular profile

tinydm-run-session.sh

@@ -91,13 +91,12 @@ run_session() {
 		export XDG_CURRENT_DESKTOP="$desktop_names"
 	fi
 
-	# Check if profile or session profile requests tinydm to start a dbus
-	# session. This is indicated by exporting the value "true" in a
-	# TINYDM_START_DBUS_SESSION environment variable in either profile
+	# Check if profile requests tinydm to start a dbus session. This
+	# is indicated by exporting a TINYDM_START_DBUS_SESSION=true
+	# environment variable in the profile
 	if [ -z "$DBUS_SESSION_BUS_ADDRESS" ] &&
 	   [ "$TINYDM_START_DBUS_SESSION" = "true" ] &&
 	   [ "$(command -v dbus-launch)" ]; then
-		cmd=$(command -v "$cmd")
 		cmd="$(command -v dbus-launch) --exit-with-x11 $cmd"
 	fi