Merged from trunk 6132:6146

Merged from trunk 6132:6146

When emerge automatically resumes, add --ignore-default-opts to the
command line in order to prevent things like --ask from leaking in via
EMERGE_DEFAULT_OPTS.  Thanks to Peter Weller <welp@gentoo.org> for
reporting.

For bug #169046, fill in the --tree display with "nomerge" nodes so that
the user can always see at lease 1 parent on any non-root node.
Packages may appear in the display list multiple times, and will be
marked "nomerge" when their position in the list does not correspond to
actual merge order.

Fix types.InstanceType test which is failing now for some reason.

remove category regex, dumb idea, sorry I did it (WarnerBro)

s/node/selected_parent/ for clarity

For bug #138840, show a more informative message when waiting for a
distfiles lock due to parallel-fetch.  Thanks to David Watzke
<david@watzke.cz> for the initial patch.

Add missing sys import.

svn path=/main/branches/prefix/; revision=6150