revlog: update pure nodecache start lookup offset on insertion
test-storage.py is failing in pure builds because the population of the node
cache isn't accounting for the new starting offset after a revlog insertion.
This commit updates the node cache start offset to account for insertions.
I'm not 100% convinced this is the ideal solution. But it works and seems
correct.
Differential Revision: https://phab.mercurial-scm.org/D4996
https://bz.mercurial-scm.org/1089
$ hg init
$ mkdir a
$ echo a > a/b
$ hg ci -Am m
adding a/b
$ hg rm a
removing a/b
$ hg ci -m m a
$ mkdir a b
$ echo a > a/b
$ hg ci -Am m
adding a/b
$ hg rm a
removing a/b
$ cd b
Relative delete:
$ hg ci -m m ../a
$ cd ..