Bug 917440 - Don't attempt to read stdout of xpcshell process when running interactively. r=ted

testing/xpcshell/runxpcshelltests.py

@@ -199,14 +199,15 @@ class XPCShellTestThread(Thread):
         # Processing of incremental output put here to
         # sidestep issues on remote platforms, where what we know
         # as proc is a file pulled off of a device.
-        while True:
-            line = proc.stdout.readline()
-            if not line:
-                break
-            self.process_line(line)
+        if proc.stdout:
+            while True:
+                line = proc.stdout.readline()
+                if not line:
+                    break
+                self.process_line(line)
 
-        if self.saw_proc_start and not self.saw_proc_end:
-            self.has_failure_output = True
+            if self.saw_proc_start and not self.saw_proc_end:
+                self.has_failure_output = True
 
         return proc.communicate()