Rename a database that has connections

I've been helping out several customers recently who all seem to be
wrestling with the same issue: wanting to update/refresh non-production
databases from the latest corresponding prod version. Typically they
have (fairly complex) scripts that at some point attempt to restore a
dump into new database and then rename the to-be-retired db out of the
way and rename the newly restored one to take over.

In many cases such scripts would be simplified if a database could be
renamed without requiring its connections terminated. I've been asked
several times if this could be added... so I've caved in a done a patch
that allows this.

The default behavior is unchanged - it is required to specify an
additional trailing FORCE keyword to elicit the more brutal behavior.
Note that existing connections to the renamed database are unaffected,
but obviously SELECT current_database() returns the new name (in the
next transaction).

regards

Mark