context: avoid extra parents lookups Resolving parents requires reading from the changelog, which is a few attributes and function calls away. Parents lookup occurs surprisingly often. Micro optimizing the code to avoid redundant lookups of parents appears to make `hg log` on my Firefox repo a little faster: before: 24.91s after: 23.76s delta: -1.15s (95.4% of original)

context: optimize _parents() This patch avoids some extra attribute lookups and list mutations. This micro-optimization seems to result in a minor speedup for `hg log` on my Firefox repo: before: 25.35s after: 24.91s delta: -0.44s (98% of original) Not the biggest gain. But every little bit helps.