This allows multiple efficient missing ancestor queries against the same set of
bases. In upcoming patches we'll also define ways to grow the set of bases.
The fact that the test output hasn't changed establishes this patch's
correctness.
I was wondering if revisions in the initial set that are still ancestors of other
elements in the initial set were yielded by `changelog.ancestors`. I now have my
answer (they do) and Mercurial has a new test.
ninteresting indicates the number of non-zero elements in the interesting
array, not the number of elements in the final list. Since elements in
interesting can stand for more than one gca, limiting the number of results to
ninteresting is an error.
Tests for issue3984 are included.
This also makes the perfancestorset command use lazy membership testing. In a
linear repository with over 400,000 commits, without this patch, hg
perfancestorset takes 0.80 seconds no matter how far behind we're looking.
With this patch, hg perfancestorset -- X takes:
Rev X Time
-1 0.00s
-4000 0.01s
-20000 0.04s
-80000 0.17s
-200000 0.43s
-300000 0.69s
0 0.88s
Thus, for revisions close to tip, we're up to several orders of magnitude
faster. At 0 we're around 10% slower.
