pgsql: Make "unexpected EOF" messages DEBUG1 unless in an open transact

Make "unexpected EOF" messages DEBUG1 unless in an open transaction

"Unexpected EOF on client connection" without an open transaction
is mostly noise, so turn it into DEBUG1. With an open transaction it's
still indicating a problem, so keep those as ERROR, and change the message
to indicate that it happened in a transaction.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/916d589a10185bb30fc77923029d806f5907ab1e

Modified Files
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src/backend/commands/copy.c | 6 +++---
src/backend/tcop/fastpath.c | 19 ++++++++++++++++---
src/backend/tcop/postgres.c | 38 ++++++++++++++++++++++++++++++++------
3 files changed, 51 insertions(+), 12 deletions(-)