pgsql: Fix parallel pg_restore to handle comments on POST_DATA items co

Fix parallel pg_restore to handle comments on POST_DATA items correctly.

The previous coding would try to process all SECTION_NONE items in the
initial sequential-restore pass, which failed if they were dependencies of
not-yet-restored items. Fix by postponing such items into the parallel
processing pass once we have skipped any non-PRE_DATA item.

Back-patch into 9.0; the original parallel-restore coding in 8.4 did not
have this bug, so no need to change it.

Report and diagnosis by Arnd Hannemann.

Branch
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REL9_0_STABLE

Details
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http://git.postgresql.org/pg/commitdiff/b22e2d6b0254e480f7ffa83ba17cd7a9e4cace98

Modified Files
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src/bin/pg_dump/pg_backup_archiver.c | 65 ++++++++++++++++++++++++++--------
1 files changed, 50 insertions(+), 15 deletions(-)