Fixing write race condition

[PlutoMatt]

Fixing a race condition that can occur when copying files. Previously the finished callback was called when the file read stream was done reading, but potentially before the write stream was done.

[catto]

Same here. When I try to copy files, sometimes it fails with an error of fs.stat when confirm flag is true even if all files are copied successfully. Possibly it occurs by calling the finished callback before creating toFiles.

[davglass]

Published in cpr@3.0.0