!!! existing preserved libs:
>>> package: dev-libs/openssl-1.1.0g-r1
 *  - /usr/lib/libcrypto.so.1.0.0
 *      used by /usr/bin/ssh (net-misc/openssh-7.5_p1-r3)
 *      used by /usr/bin/ssh-add (net-misc/openssh-7.5_p1-r3)
 *      used by /usr/bin/ssh-agent (net-misc/openssh-7.5_p1-r3)
 *      used by 11 other files
 *  - /usr/lib/libssl.so.1.0.0
 *      used by /usr/lib/libldap-2.4.so.2.10.7 (net-nds/openldap-2.4.44)
 *      used by /usr/lib/libldap_r-2.4.so.2.10.7 (net-nds/openldap-2.4.44)
 *      used by /usr/lib/python2.7/lib-dynload/_ssl.so (dev-lang/python-2.7.14)
 *      used by /usr/lib/python3.4/lib-dynload/_ssl.cpython-34m.so (dev-lang/python-3.4.5)
Use emerge @preserved-rebuild to rebuild packages using these libraries
 * After world updates, it is important to remove obsolete packages with
 * emerge --depclean. Refer to `man emerge` for more information.