397e5111b5
Preserve CHUNK_MAP_UNZEROED when allocating small runs, because it is possible that untouched pages will be returned to the tree of clean runs, where the CHUNK_MAP_UNZEROED flag matters. Prior to the conversion from CHUNK_MAP_ZEROED, this was already a bug, but in the worst case extra zeroing occurred. After the conversion, this bug made it possible to incorrectly treat pages as pre-zeroed.