The heuristics algorithm find possible candidates for move/copy and then check
whether they are actually a copy or move. In some cases, there can be lot of
candidates possible which can actually slow down the algorithm.
This patch introduces a config option
experimental.copytrace.movecandidateslimit using which one can limit the
candidates to check. The limit defaults to 100.
Thanks to Yuya for suggesting to skip copytracing for that file with a