* lisp/vc/vc.el (vc-deduce-fileset): Set buffer to the base buffer, if any (bug#63949). That's to replace the more complex previous strategy. vc-deduce-fileset is allowed to change the current buffer, so why not do it for that case. (vc-deduce-fileset-1): Delete, moving the meat of the logic back to vc-deduce-fileset.