Merged from trunk 6108:6129

Merged from trunk 6108:6129

Use an alarm signal to implement a timeout when rsync is fetching the
server timestamp file, since rsync's --timeout option doesn't apply to
the initial connection attempt.

Make sure pids are appropriately removed from
portage.process.spawned_pids.

please be --quiet emerge. still need to hunt down one more newline
(Solar)

Add compatibility code to avoid the GNU specific --reference option of
chmod.  Thanks to Timothy Redaelli <drizzt@gentoo.org>.

For consistency, remove exit code 2 (protocol incompatibility) from the
other list of rsync exit codes.

Fix broken except statement syntax.

Fix the rest of the broken except statement syntax.

Fix broken rsync exitcode shift.

Remove unnecessary print statement reported by solar.

Even if there's no timestamp available locally, fetch the timestamp
anyway as an initial probe to verify that the server is responsive.
This protects us from hanging indefinitely on a connection attempt to an
unresponsive server which rsync's --timeout option does not prevent.

For bug #168646, remove --prune-empty-dirs from PORTAGE_RSYNC_OPTS since
it's only a small optimization and it's inconvenient to force
>=rsync-2.6.4 on server admins at this time.  If users desire, they can
still add it to PORTAGE_RSYNC_EXTRA_OPTS.

svn path=/main/branches/prefix/; revision=6131