psql crashes postmaster

Krzysztof Czuma (czuma@Elektron.pl) reports a bug with a severity of 2
The lower the number the more severe it is.

Short Description
psql crashes postmaster

Long Description
PostgreSQL 7.0.3, SunOS amber 5.8 Generic_108529-05 i86pc i386 i86pc
gcc version 2.95.2

postmaster crashes after user try to login to database from psql

Sample Code
psql
Password:
psql: pqReadData() -- backend closed the channel unexpectedly.
        This probably means the backend terminated abnormally
        before or while processing the request.
psql
psql: connectDBStart() -- connect() failed: No such file or directory
        Is the postmaster running at 'localhost'
        and accepting connections on Unix socket '5432'?

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