Don't return the address of a P2SH of a P2SH

[jnewbery]

be066fa added an RPC to decode a hex input script. The returned object is:

{
  "asm":"asm",   (string) Script public key
  "hex":"hex",   (string) hex encoded public key
  "type":"type", (string) The output type
  "reqSigs": n,    (numeric) The required signatures
  "addresses": [   (json array of string)
     "address"     (string) bitcoin address
     ,...
  ],
  "p2sh","address" (string) script address.
}

That "p2sh" return value is the address of a P2SH with the hex input script as the redeem script.

If the input script is already a P2SH script, this doesn't make sense (we can't wrap a P2SH in a P2SH). Only return a P2SH address if the input script is not a P2SH script.

[ryanofsky]

Should probably drop the isNull check because a value can't be both a string and a null at the same time.

Also maybe drop the parens around && conditions (searching for "&&" in this file shows no parens used in the other cases).

[jnewbery]

Thanks. Both done.

[jnewbery]

@ryanofsky's suggestions added and rebased.

[sipa]

utACK

[luke-jr]

"Incorporated suggested changes from @ryanofsky." doesn't belong in the commit description (it will ping him every time the commit goes somewhere..)

[MarcoFalke]

Agree. Also please don't put irrelevant information in the commit subject line.

[jnewbery]

Fixed commit description.

[laanwj]

utACK

[laanwj]

I think looking at the generated JSON here instead of the script object itself is a bit confusing, but I tend to agree it's the best way to go here to not have to repeat ExtractDestinations.