revlog: remove side effect from failed nt_init() If nt_init() successfully allocates memory for the node tree but then runs out of memory while trying to insert nullid into it, it will leave the node tree pointer set on the index object. That means that future node tree operations will think that the tree is properly initialized. It seems very unlikely to make a difference in practice (if nt_init() runs out of memory, not much else will probably work), but since I spotted it, I figured I might as well fix it. Differential Revision: https://phab.mercurial-scm.org/D4028

revlog: remove micro-optimization for looking up only nullid index_find_node() would call nt_find() before initializing the node tree. nt_find() would then return -2 unless the requested revision was the null revision. I can't imagine what scenario that is optimizing for, and doing the initialization earlier makes the code simpler and easier to follow, so that's what this patch does. Differential Revision: https://phab.mercurial-scm.org/D4027

revlog: remove unnecessary output parameter from node_check() The "nodelen" output parameter is always set to 20 if the function returns successfully. Differential Revision: https://phab.mercurial-scm.org/D4026