Fix error return value from rename()

Fuse operations expect negated errno values.

Author: Quentin Rameau

ChangeLog.rst

@@ -1,3 +1,8 @@
+Unreleased Changes
+------------------
+
+* Fixed error code returned by rename(), allowing proper fallback.
+
 Release 3.4.0 (2018-06-29)
 --------------------------
 

sshfs.c

@@ -2316,7 +2316,7 @@ static int sshfs_rename(const char *from, const char *to, unsigned int flags)
 	int err;
 
 	if(flags != 0)
-		return EINVAL;
+		return -EINVAL;
 
 	if (sshfs.ext_posix_rename)
 		err = sshfs_ext_posix_rename(from, to);