fast-export: quote paths with spaces

fast-export: quote paths with spaces

A path containing a space must be quoted when used as an
argument to either the copy or rename commands (because
unlike other commands, the path is not the final thing on
the line for those commands).

Commit 6280dfdc3b (fast-export: quote paths in output,
2011-08-05) previously attempted to fix fast-export's
quoting by passing all paths through quote_c_style().
However, that function does not consider the space to be a
character which requires quoting, so let's special-case the
space inside print_path(). This will cause space-containing
paths to also be quoted in other commands where such quoting
is not strictly necessary, but it does not hurt to do so.

The test from 6280dfdc3b did not detect this because, while
it does introduce renames in the export stream, it does not
actually turn on rename detection, so they were presented as
pairs of deletions/adds. Using "-M" reveals the bug.

Signed-off-by: Jay Soffian <jaysoffian@gmail.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>