Index: configure.in
===================================================================
--- configure.in	(revision 7000)
+++ configure.in	(working copy)
@@ -411,6 +411,9 @@
 AC_DEFINE_UNQUOTED(SVN_PATH_LOCAL_SEPARATOR, '/',
         [Defined to be the path separator used on your local filesystem])
 
+AC_DEFINE_UNQUOTED(SVN_NULL_DEVICE_NAME, "/dev/null",
+        [Defined to be the null device for the system])
+
 dnl Find a python 2.X binary, test cases will not run with Python 1.X
 AC_PATH_PROG(PYTHON2, python2, none)
 if test "$PYTHON2" = "none"; then
Index: subversion/libsvn_repos/hooks.c
===================================================================
--- subversion/libsvn_repos/hooks.c	(revision 7000)
+++ subversion/libsvn_repos/hooks.c	(working copy)
@@ -50,7 +50,7 @@
               svn_boolean_t check_exitcode,
               apr_pool_t *pool)
 {
-  apr_file_t *read_errhandle, *write_errhandle;
+  apr_file_t *read_errhandle, *write_errhandle, *null_handle;
   apr_status_t apr_err;
   svn_error_t *err;
   int exitcode;
@@ -62,12 +62,20 @@
     return svn_error_createf
       (apr_err, NULL, "can't create pipe for '%s' hook", cmd);
 
+  /* Redirect stdout to the null device */
+  apr_err = apr_file_open (&null_handle, SVN_NULL_DEVICE_NAME, APR_WRITE,
+                           APR_OS_DEFAULT, pool);
+  if (apr_err)
+    return svn_error_createf
+      (apr_err, NULL, "can't create null stdout for '%s' hook", cmd);
+
   err = svn_io_run_cmd (".", cmd, args, &exitcode, &exitwhy, FALSE,
-                        NULL, NULL, write_errhandle, pool);
+                        NULL, null_handle, write_errhandle, pool);
 
   /* This seems to be done automatically if we pass the third parameter of
      apr_procattr_child_in/out_set(), but svn_io_run_cmd()'s interface does
-     not support those parameters. */
+     not support those parameters. We need to close the write end of the
+     pipe so we don't hang on the read end later, if we need to read it. */
   apr_err = apr_file_close (write_errhandle);
   if (!err && apr_err)
     return svn_error_create
@@ -98,12 +106,18 @@
     }
 
   /* Hooks are fallible, and so hook failure is "expected" to occur at
-     times.  When such a failure happens we still want to close the pipe */
+     times.  When such a failure happens we still want to close the pipe
+     and null file */
   apr_err = apr_file_close (read_errhandle);
   if (!err && apr_err)
     return svn_error_create
-      (apr_err, NULL, "can't close read end of stdout pipe");
+      (apr_err, NULL, "can't close read end of stderr pipe");
 
+  apr_err = apr_file_close (null_handle);
+  if (!err && apr_err)
+    return svn_error_create
+      (apr_err, NULL, "can't close null file");
+
   return err;
 }
 
Index: svn_private_config.hw
===================================================================
--- svn_private_config.hw	(revision 7000)
+++ svn_private_config.hw	(working copy)
@@ -36,6 +36,9 @@
 /* Path separator for local filesystem */
 #define SVN_PATH_LOCAL_SEPARATOR '\\'
 
+/* Name of system's null device */
+#define SVN_NULL_DEVICE_NAME "nul"
+
 /* Link local repos access library to client */
 #define SVN_LIBSVN_CLIENT_LINKS_RA_LOCAL