mysqld_safe bug with --basedir option

When running multiple instances of mariadb, if mysqld_safe is passed the "basedir" option, it will fail to start the second instance of mariadb with:

[zimbra@zre-ldap005 ~]$ /opt/zimbra/common/bin/mysqld_safe --basedir=/opt/zimbra/common --defaults-file=/opt/zimbra/conf/antispam-my.cnf --external-locking --malloc-lib=/opt/zimbra/common/lib/libtcmalloc_minimal.so --datadir=/opt/zimbra/data/amavisd/mysql/data --log-error=/opt/zimbra/log/antispam-mysqld.log --ledir=/opt/zimbra/common/sbin
151230 14:57:42 mysqld_safe Adding '/opt/zimbra/common/lib/libtcmalloc_minimal.so' to LD_PRELOAD for mysqld
151230 14:57:43 mysqld_safe Logging to '/opt/zimbra/log/antispam-mysqld.log'.
151230 14:57:43 mysqld_safe A mysqld process already exists

Removing the --basedir option allows it to successfully start:
[zimbra@zre-ldap005 ~]$ /opt/zimbra/common/bin/mysqld_safe --defaults-file=/opt/zimbra/conf/antispam-my.cnf --external-locking --malloc-lib=/opt/zimbra/common/lib/libtcmalloc_minimal.so --datadir=/opt/zimbra/data/amavisd/mysql/data --log-error=/opt/zimbra/log/antispam-mysqld.log --ledir=/opt/zimbra/common/sbin 151230 14:58:04 mysqld_safe Adding '/opt/zimbra/common/lib/libtcmalloc_minimal.so' to LD_PRELOAD for mysqld
151230 14:58:04 mysqld_safe Logging to '/opt/zimbra/log/antispam-mysqld.log'.
151230 14:58:04 mysqld_safe Starting mysqld daemon with databases from /opt/zimbra/data/amavisd/mysql/data

Note that this is the exact basedir value provided in the cnf file:
[zimbra@zre-ldap005 conf]$ grep basedir antispam-my.cnf
basedir = /opt/zimbra/common

It appears the issue is that the other mysql instance is running with the same basedir value:
zimbra 2712 1 0 09:46 ? 00:00:00 /bin/sh /opt/zimbra/common/bin/mysqld_safe --defaults-file=/opt/zimbra/conf/my.cnf --external-locking --log-error=/opt/zimbra/log/mysql_error.log --malloc-lib=/opt/zimbra/common/lib/libtcmalloc_minimal.so --ledir=/opt/zimbra/common/sbin
zimbra 2917 2712 0 09:46 ? 00:00:14 /opt/zimbra/common/sbin/mysqld --defaults-file=/opt/zimbra/conf/my.cnf --basedir=/opt/zimbra/common --datadir=/opt/zimbra/db/data --plugin-dir=/opt/zimbra/common/lib/plugin --external-locking --log-error=/opt/zimbra/log/mysql_error.log --pid-file=/opt/zimbra/log/mysql.pid --socket=/opt/zimbra/data/tmp/mysql/mysql.sock --port=7306

However, there is nothing wrong with two instances of mysqld having the same value for basedir, as the entire point is for mysqld to be sharing the same binaries.