fix: void Xsession fail when $HOME is full

When user home is full,
scripts write to a file in user home will failed.

After redirect stdout and stderr to ERRFILE,
aka $HOME/.xsession-errors,
this script echo a line to that file.

This echo might failed and make this script exit with error.
In that case, the session leader will not able to even start.

Releated: linuxdeepin/developer-center#4685
Releated: linuxdeepin/dde-daemon#526

debian/local/Xsession

@@ -94,7 +94,9 @@ fi
 
 exec >>"$ERRFILE" 2>&1
 
-echo "$PROGNAME: X session started for $LOGNAME at $(date)"
+# This echo might fail as we just redirect stderr.
+# Just ignore that failure here.
+echo "$PROGNAME: X session started for $LOGNAME at $(date)" || true
 
 # sanity check; is our session script directory present?
 if [ ! -d "$SYSSESSIONDIR" ]; then