[glom] tests_selfhosting_new_then_image: Output clues about the failure.

[Murray Cumming <murrayc src gnome org>]

commit 1bc3c2f91dbb2d559f103c3d5373cc67d5831c2d
Author: Murray Cumming <murrayc murrayc com>
Date:   Mon Nov 17 11:52:10 2014 +0100

    tests_selfhosting_new_then_image: Output clues about the failure.

 tests/test_selfhosting_new_then_image.cc |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)
---
diff --git a/tests/test_selfhosting_new_then_image.cc b/tests/test_selfhosting_new_then_image.cc
index 678a31d..6ca7f54 100644
--- a/tests/test_selfhosting_new_then_image.cc
+++ b/tests/test_selfhosting_new_then_image.cc
@@ -134,7 +134,10 @@ static bool test(Glom::Document::HostingMode hosting_mode)
 
   if(binary_set->binary_length != binary_read->binary_length)
   {
-    std::cerr << G_STRFUNC << ": Failure: The value read's data length was not equal to that of the value 
set." << std::endl;
+    std::cerr << G_STRFUNC << ": Failure: The value read's data length ("
+      << binary_read->binary_length <<
+      ") was not equal to that of the value set ("
+      << binary_set->binary_length << ")" << std::endl;
     return false;
   }