Code review comment for lp:~jameinel/bzr/1.17-extract-one-time

While investigating 'annotate' performance, I was surprised to find that _simple_annotate was 4x slower than the optimized path (even with the KnownGraph improvements). (90ms versus 370ms)

It turns out that at least one problem was that doing "get_record_stream(..., True)" was causing the _ContentMapGenerator to read the raw records 2 times. One time in __init__, and then a second time in _work.

This patch just removes the second call. Which makes _simple_annotate 265ms (3:1). This would effect any time we have code that tries to get fulltexts. So it should also impact things like building the working tree, etc.