In make_simple_backup(), if the rename() failed because we tried

to rename a directory over a file or visa versa, try to handle it.

backup.c

@@ -55,23 +55,37 @@ char *get_backup_name(char *fname)
 /* simple backup creates a backup with a suffix in the same directory */
 static int make_simple_backup(char *fname)
 {
+	int rename_errno;
 	char *fnamebak = get_backup_name(fname);
 
 	if (!fnamebak)
 		return 0;
 
-	if (do_rename(fname, fnamebak) != 0) {
-		/* cygwin (at least version b19) reports EINVAL */
-		if (errno != ENOENT && errno != EINVAL) {
-			rsyserr(FERROR, errno,
-				"rename %s to backup %s",
-				safe_fname(fname), safe_fname(fnamebak));
-			return 0;
+	while (1) {
+		if (do_rename(fname, fnamebak) == 0) {
+			if (verbose > 1) {
+				rprintf(FINFO, "backed up %s to %s\n",
+					safe_fname(fname),
+					safe_fname(fnamebak));
+			}
+			break;
 		}
-	} else if (verbose > 1) {
-		rprintf(FINFO, "backed up %s to %s\n",
+		/* cygwin (at least version b19) reports EINVAL */
+		if (errno == ENOENT || errno == EINVAL)
+			break;
+
+		rename_errno = errno;
+		if (errno == EISDIR && do_rmdir(fnamebak) == 0)
+			continue;
+		if (errno == ENOTDIR && do_unlink(fnamebak) == 0)
+			continue;
+
+		rsyserr(FERROR, rename_errno, "rename %s to backup %s",
 			safe_fname(fname), safe_fname(fnamebak));
+		errno = rename_errno;
+		return 0;
 	}
+
 	return 1;
 }