vchoi_fork

Add a test for single-page metadata (SPMDE) writes.  Mention in a
comment to myself that I need to reduce code duplication with the MPMDE
test.

In vfd_read_each_equals(), print the correct expected value when there
is a discrepancy.

No functional change intended: correct a comment in
vfd_read_each_equals.  Fix indentation in the test_raw_data_handling()
header comment.