table_open_cache increase issue - MariaDB 10.2
I can see 3 different reasons why MariaDB might reset this variable. In order of most to least likely explanation:


You have another .cnf file where the table_open_cache variable is being set to 4895. 
The MariaDB Systemd unit file (or SysV init script on older Linux versions) is overwriting the variable value you've set. 
You're running a non-standard MariaDB server that's been compiled with a hard-coded value for table_open_cache. (Unlikely!)


Additionally, it's possible that another software (such as cPanel) might change the variable dynamically after MariaDB has started.

To see which options the MariaDB server will get from the option files, run:

mysqld --print-defaults 


To find all the places where the MariaDB server is looking for .cnf files, run:

mysqld --verbose --help | grep -A 1 'Default options are read'


You can then grep each of these files to see if you find any instances of table_open_cache or table-open-cache. 

For reference, you should be able to see the current value of the variable with:

show global variables like 'table_open_cache';


And you may also want to consult this page in the MariaDB Knowledge Base: Optimizing table_open_cache.