[SalesForce] Why are where clause comparison operators case-sensitive when using SOQL to query custom metadata

When using SOQL to query custom metadata records, the comparison in my where clause appears to be case-sensitive. Example:

MyField__c is a text field that is NOT unique and NOT case sensitive

select 
    MyField__c 
from 
    MyCustomMetadataType__mdt
where
    MyField__c = 'testvalue'

Results: 0 records

The record is stored as 'TestValue' and the following query finds it:

select 
    MyField__c 
from 
    MyCustomMetadataType__mdt
where
    MyField__c = 'TestValue'

Results 1 record

This is contrary to SOQL documentation:
https://developer.salesforce.com/docs/atlas.en-us.soql_sosl.meta/soql_sosl/sforce_api_calls_sosl_where.htm

Expression is true if the value in the specified fieldName equals the
specified value in the expression. String comparisons using the equals
operator are case-sensitive for unique case-sensitive fields and
case-insensitive for all other fields.

Am I missing something or are queries against custom metadata working differently?

EDIT
Salesforce has logged this as a known issue and it is under review: https://success.salesforce.com/issues_view?id=a1p3A0000001CvkQAE