This is not as risky as it may look like, in fact I think it is pretty save and if anything the previous behavior is the wrong one (not saying it doesn't need testing).

How much time can pass from https://github.com/bitcoin/bitcoin/blob/master/src/miner.cpp#L308 (called from https://github.com/bitcoin/bitcoin/blob/master/src/rpcmining.cpp#L359) to https://github.com/bitcoin/bitcoin/blob/master/src/rpcmining.cpp#L369 ?
The nonce is set to zero in both cases and the bits can only change in the second UpdateTime if we're on testnet.

Untested ACK. Those calls look redundant.

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NAK. Obviously wrong. Read the code. If called frequently, those static vars act as a cache.

I see, so removing this would cause the cached nTime to be used.
I think removing the nNonce = 0 assignment is safe though, no?
A cached zero should be as good as a fresh one.

Undo ACK; You're right, @jgarzik.

Sharp catch @jgarzik