filelog: test behaviour for data starting with "\1\n"
Because "\1\n" is a separator for metadata, data starting with "\1\n" is
handled specifically. It was not tested.
size() call return incorrect data if original data had been "\1\n-escaped".
There's no obvious way to fix it for now, just flag the error in the code
and add an "expected failure" kind of test.
ERROR: FIXME: This is a known failure of filelog.size for data starting with \1\n
OK.