mysql ignoring NULL while using group by and where condition
===

I am able to replicate my issue with a very simple case..  
**Explanation**  
I have a very simple table `my_table` with one column `column1`. 

    create table my_table (column1 varchar(58));
I have few values for this column, `NULL` is also one of them.

    insert into my_table (column1) values ('value1'), ('value1'), ('value2'), (null), ('value2');

**Problem**  
When I try to query for  ` group by column1` It is giving expected results by grouping all `NULL`s together. However if I add a `where` clause on `column1` something like 

    select count(1) as value_count, column1 from my_table where column1 <> 'value1' group by column1;


It is ignoring both `value1` and `NULL` where I was expecting to ignore only `value1`.

With this simple case I could get a workaround for this by adding an `OR` condition, But it is a real pain to add this condition all over in my original case. 

Could someone can explain me better why this behavior and how can I fix this?

 