Index: tools/gformat.py
===================================================================
--- tools/gformat.py	(revision 14055)
+++ tools/gformat.py	(revision 14093)
@@ -1945,21 +1945,22 @@
       stack = ['root']
       prev_depth = 0
-      for line in open('lvrouted.mytree').readlines():
-        depth = line.count('\t')
-        ip = line.strip().split()[0]
-      
-        if prev_depth < depth:
-          try:
-            parents[ip2host[ip]].append(ip2host[stack[-1]])
-          except KeyError as e:
-            print >> stderr, "# Unable to find %s in configuration files" % e.args[0]
-          stack.append(ip)
-        elif prev_depth > depth:
-          stack = stack[:(depth - prev_depth)]
-        elif prev_depth == depth:
-          try:
-            parents[ip2host[ip]].append(ip2host[stack[-1]])
-          except KeyError as e:
-            print >> stderr, "# Unable to find %s in configuration files" % e.args[0]
+      if os.path.isfile('lvrouted.mytree'):
+        for line in open('lvrouted.mytree').readlines():
+          depth = line.count('\t')
+          ip = line.strip().split()[0]
+        
+          if prev_depth < depth:
+            try:
+              parents[ip2host[ip]].append(ip2host[stack[-1]])
+            except KeyError as e:
+              print >> stderr, "# Unable to find %s in configuration files" % e.args[0]
+            stack.append(ip)
+          elif prev_depth > depth:
+            stack = stack[:(depth - prev_depth)]
+          elif prev_depth == depth:
+            try:
+              parents[ip2host[ip]].append(ip2host[stack[-1]])
+            except KeyError as e:
+              print >> stderr, "# Unable to find %s in configuration files" % e.args[0]