Make hg add foo; hg mv foo bar work. - foo will be removed (the user has a copy of its contents in bar) - bar will not be marked as a copy (there was no committed version of foo). We print a warning telling that to the user. Fixes issue269.

abort: Failed to parse .../t/.hg/hgrc
File contains no section headers.
file: .../t/.hg/hgrc, line: 1
'invalid\n'