Don't bother with ReleaseNotes.txt if not present

git-svn-id: https://svn.resiprocate.org/rep/resiprocate/main@8346 ddefafc4-47db-0310-ae44-fa13212b10f2

Author: adamroach

buginfo.pl

@@ -37,7 +37,11 @@
 }
 
 &exec ("svnversion");
-&exec ("head ReleaseNotes.txt");
+
+if (-e 'ReleaseNotes.txt')
+{
+  &exec ("head ReleaseNotes.txt");
+}
 
 if ($uname =~ /Darwin/i)
 {