branchcache: move the processing of the new data in a dedicated method
In a future changeset, this will allow the V3 of the branch cache to use a fast
path when possible.
#require test-repo jshint hg10
$ . "$TESTDIR/helpers-testrepo.sh"
run jshint on all tracked files ending in .js except vendored dependencies
$ cd "`dirname "$TESTDIR"`"
$ testrepohg locate 'set:**.js' \
> 2>/dev/null \
> | xargs jshint