plugins.auth_ed25519 fails in buildbot with undefined symbol: inflate

plugins.auth_ed25519                     w2 [ fail ]

        Test ended at 2019-07-23 15:55:40

CURRENT_TEST: plugins.auth_ed25519

mysqltest: At line 35: query 'connect con1, localhost, test1, secret' failed: 1045: Plugin client_ed25519 could not be loaded: /usr/local/mariadb-10.2.26-linux-x86_64/lib/plugin//client_ed25519.so: undefined symbol: inflate

The result from queries just before the failure was:

< snip >

PLUGIN_NAME	ed25519

PLUGIN_VERSION	1.0

PLUGIN_STATUS	ACTIVE

PLUGIN_TYPE	AUTHENTICATION

PLUGIN_TYPE_VERSION	2.1

PLUGIN_LIBRARY	auth_ed25519.so

PLUGIN_LIBRARY_VERSION	1.13

PLUGIN_AUTHOR	Sergei Golubchik

PLUGIN_DESCRIPTION	Elliptic curve ED25519 based authentication

PLUGIN_LICENSE	GPL

LOAD_OPTION	ON

PLUGIN_MATURITY	Stable

PLUGIN_AUTH_VERSION	1.0

create user test1@localhost identified via ed25519 using 'ZIgUREUg5PVgQ6LskhXmO+eZLS0nC8be6HPjYWR4YJY';

show grants for test1@localhost;

Grants for test1@localhost

GRANT USAGE ON *.* TO 'test1'@'localhost' IDENTIFIED VIA ed25519 USING 'ZIgUREUg5PVgQ6LskhXmO+eZLS0nC8be6HPjYWR4YJY'

connect(localhost,test1,public,test,PORT,SOCKET);

connect con1, localhost, test1, public;

ERROR 28000: Plugin client_ed25519 could not be loaded: /usr/local/mariadb-10.2.26-linux-x86_64/lib/plugin//client_ed25519.so: undefined symbol: inflate