Thread: pgsql: Add some code to CREATE DATABASE to check for pre-existing

Log Message:
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Add some code to CREATE DATABASE to check for pre-existing subdirectories
that conflict with the OID that we want to use for the new database.
This avoids the risk of trying to remove files that maybe we shouldn't
remove.  Per gripe from Jon Lapham and subsequent discussion of 27-Sep.

Modified Files:
--------------
    pgsql/src/backend/access/transam:
        xlog.c (r1.251 -> r1.252)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/transam/xlog.c.diff?r1=1.251&r2=1.252)
    pgsql/src/backend/commands:
        dbcommands.c (r1.185 -> r1.186)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/dbcommands.c.diff?r1=1.185&r2=1.186)