bitcoin/bitcoin — pull request #2129 by gmaxwell (2012-12-26 18:08:57+00:00)
Title: If the prio. will be enough after the next block don't force fees. [wallet]

If the user was really after the fastest possible confirmation times
they would be manually setting a fee. In cases where the wallet builds
a transaction with a priority that is too low to qualify as free until
the next block, go ahead without a fee. Confirmation frequently takes
multiple blocks even when a minimum fee is provided.