[racket] db connection-pool tip

A sentence or two documenting the custodian behavior for connection 
pools might be useful.

The behavior is what you'd expect if you considered it, but, at least in 
my anecdote, I took a while to consider it.

BTW, I am really liking the "db" collection.

Neil

Matthias Felleisen wrote at 08/21/2012 07:09 PM:
> Are you saying that Ryan should add an appropriate warning to the documentation? -- Matthias
>
>
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> On Aug 21, 2012, at 6:33 PM, Neil Van Dyke wrote:
>
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>> When using the "db" collection's "connection-pool" procedure, important safety tip: it uses the "current-custodian" from the context in which "connection-pool" is applied.
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