bitcoin/bitcoin — pull request #4962 by ENikS (2014-09-22 20:33:16+00:00)
Title: Error: Vector out of bounds in GetKey()

If 32 == vchData.size():
vchData[32] -> Out of bounds (Runtime error)
vchData.begin() + 32 -> vchData.end() (Perfectly valid operation)

If 33 == vchData.size(): - both notations work.