diff --git a/tests/run-tests.py b/tests/run-tests.py
--- a/tests/run-tests.py
+++ b/tests/run-tests.py
@@ -749,7 +749,8 @@ def run(cmd, wd, options, replacements):
     Return a tuple (exitcode, output).  output is None in debug mode."""
     # TODO: Use subprocess.Popen if we're running on Python 2.4
     if options.debug:
-        proc = subprocess.Popen(cmd, shell=True, cwd=wd)
+        proc = subprocess.Popen(cmd, shell=True, cwd=wd, stdin=subprocess.PIPE)
+        proc.stdin.close()
         ret = proc.wait()
         return (ret, None)