mv: name both source and destination when rename fails

When "git mv" fails at the rename(2) syscall, the error is reported with die_errno() using only the source path: fatal: renaming 'src' failed: No such file or directory rename(2) returns ENOENT both when the source does not exist and when a directory component of the destination does not exist, and errno does not distinguish the two. Reporting only the source therefore misleads the user in the latter case: for git mv a/file b/no-such-dir/file the message blames 'a/file', which exists, and gives no hint that 'b/no-such-dir/' is the missing part. Inspecting the paths again after the failure to determine which one is at fault would be racy, since either could appear or disappear between the rename(2) and the follow-up check. Instead, simply name both the source and the destination in the message and let the reader see which one is wrong: fatal: renaming 'a/file' to 'b/no-such-dir/file' failed: No such file or directory Signed-off-by: Lucas Zamboni Orioli <lucaszam0@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>