Previously only one PUSHDATA was allowed, needlessly limiting
applications such as matching OP_RETURN contents with bloom filters that
operate on a per-PUSHDATA level. Now any combination that passes
IsPushOnly() is allowed, so long as the total size of the scriptPubKey
is less than 42 bytes. (unchanged modulo non-minimal PUSHDATA encodings)
Also, this fixes the odd bug where previously the PUSHDATA could be
replaced by any single opcode, even sigops consuming opcodes such as
CHECKMULTISIG. (20 sigops!)
These changes decode valid SIGHASH types on signatures in assembly (asm) representations of scriptSig scripts.
This squashed commit incorporates substantial helpful feedback from jtimon, laanwj, and sipa.
Pieter Wuille