Fixes reading of textual content file for REP blocks.

In the default case of using binary content files this bug has no effect.
Fixes a wrong comment about REP blocks.

The hash of the REP block doesn't represent the old data.
With the nocopy option also remove hash info from previous sync.

If we want to disable the automatic hashing assumption of copy,
we need also to remove any previous hash info already stored
in the content file by previous sync commands run without the
nocopy option.