Index: subversion/libsvn_client/diff.c
===================================================================
--- subversion/libsvn_client/diff.c	(revision 10521)
+++ subversion/libsvn_client/diff.c	(working copy)
@@ -1411,6 +1411,7 @@
   svn_wc_notify_state_t text_state = svn_wc_notify_state_unknown;
   const char *URL1, *path1, *URL2, *path2;
   svn_opt_revision_t *revision1, *revision2;
+  svn_error_t *err;

   SVN_ERR (svn_ra_init_ra_libs (&ra_baton, pool));

@@ -1475,8 +1476,19 @@
                                mimetype1, mimetype2,
                                merge_b));

-  SVN_ERR (svn_io_remove_file (tmpfile1, pool));
-  SVN_ERR (svn_io_remove_file (tmpfile2, pool));
+  /* Ignore if temporary file not found. It may have been renamed. */
+  if ((err = svn_io_remove_file (tmpfile1, pool))
+      && !APR_STATUS_IS_ENOENT(err->apr_err))
+    {
+      return err;
+    }
+  svn_error_clear (err);
+  if ((err = svn_io_remove_file (tmpfile2, pool))
+      && !APR_STATUS_IS_ENOENT(err->apr_err))
+    {
+      return err;
+    }
+  svn_error_clear (err);

   /* Deduce property diffs, and merge those too. */
   SVN_ERR (svn_prop_diffs (&propchanges, props2, props1, pool));