Created attachment 2929 [details]
debug output

Hello,

Notes from testing:
Affected openssh version - All tested (ex. 7.2p2, OpenSSH_5.3p1)
Affected OS - All tested (OpenSUSE Leap 42.2, Arch Linux, SLES 11 SP4, HP/UX)

Hence, submitting this upstream.

Concern:
When a private key (ex. key1) is used and there's a public key with the same file name+pub extension (ex. key1.pub) in the same directory, the automatic login will fail and will drop the user to the password prompt.

Sample openssh version:
santi@osuse:~> rpm -qi openssh
Name        : openssh
Version     : 7.2p2
Release     : 6.1
Architecture: x86_64
Install Date: Wed 04 Jan 2017 10:01:31 AM PHT
Group       : Productivity/Networking/SSH
Size        : 5576705
License     : BSD-2-Clause and MIT
Signature   : RSA/SHA256, Tue 18 Oct 2016 09:01:48 PM PHT, Key ID b88b2fd43dbdc284
Source RPM  : openssh-7.2p2-6.1.src.rpm
Build Date  : Tue 18 Oct 2016 09:01:15 PM PHT
Build Host  : cloud103
Relocations : (not relocatable)
Packager    : http://bugs.opensuse.org
Vendor      : openSUSE
URL         : http://www.openssh.com/
Summary     : Secure Shell Client and Server (Remote Login Program)
Description :
SSH (Secure Shell) is a program for logging into and executing commands
on a remote machine. It is intended to replace rsh (rlogin and rsh) and
provides openssl (secure encrypted communication) between two untrusted
hosts over an insecure network.

xorg-x11 (X Window System) connections and arbitrary TCP/IP ports can
also be forwarded over the secure channel.
Distribution: openSUSE Leap 42.2
santi@osuse:~> 

Observation:
Output will display the key as type 1 (debug1) and an address in debug2.
debug1: identity file key1 type 1
..
debug2: key: key1 (0x55c14718c180), explicit

Request:
More informational error/warning/info text displayed to user instead of being dropped at the password prompt.