Fix long path issue of bwc checkouts on Windows (elastic/x-pack-elasticsearch#3259)
Fix long path issue of bwc checkouts on Windows (elastic/x-pack-elasticsearch#3259)

Hopefully fixes the Windows CI failures that break on cloning the repository into a target directory with a lengthy path name.

Original commit: elastic/x-pack-elasticsearch@fe18e95d3f03fbe03b6f4004c0f5894f4373141d

coding0011/elasticsearch,scorpionvicky/elasticsearch,gfyoung/elasticsearch,nknize/elasticsearch,coding0011/elasticsearch,robin13/elasticsearch,coding0011/elasticsearch,coding0011/elasticsearch,GlenRSmith/elasticsearch,gingerwizard/elasticsearch,gfyoung/elasticsearch,uschindler/elasticsearch,gfyoung/elasticsearch,gfyoung/elasticsearch,nknize/elasticsearch,GlenRSmith/elasticsearch,gingerwizard/elasticsearch,robin13/elasticsearch,GlenRSmith/elasticsearch,gfyoung/elasticsearch,robin13/elasticsearch,scorpionvicky/elasticsearch,HonzaKral/elasticsearch,gingerwizard/elasticsearch,nknize/elasticsearch,gingerwizard/elasticsearch,uschindler/elasticsearch,GlenRSmith/elasticsearch,coding0011/elasticsearch,scorpionvicky/elasticsearch,uschindler/elasticsearch,scorpionvicky/elasticsearch,robin13/elasticsearch,uschindler/elasticsearch,nknize/elasticsearch,HonzaKral/elasticsearch,HonzaKral/elasticsearch,GlenRSmith/elasticsearch,scorpionvicky/elasticsearch,gingerwizard/elasticsearch,gingerwizard/elasticsearch,HonzaKral/elasticsearch,robin13/elasticsearch,nknize/elasticsearch,uschindler/elasticsearch,gingerwizard/elasticsearch