branches: add per branch minfreespace w/ original value as default

example: /mnt/disk0=RW,1G:/mnt/disk1=RW,2G

src/fuse_write.cpp

@@ -92,7 +92,6 @@ namespace l
 
     rv = fs::movefile_as_root(config.moveonenospc.policy,
                               config.branches,
-                              config.minfreespace,
                               fi_->fusepath,
                               &fi_->fd);
     if(rv == -1)