Content Modeling: set custom validation error when using Regular Expressions

As a CMS admin, when I am defining a property on a content type and using the "Regular Expression" option to set a validation rule, I want to be able to define a custom error message (instead of the regular expression rule appearing in the validation error).

Ex: if I want to require a year between 1900-2100, I can use the regular expression:

^(19|20)\d{2}$

When an editor is entering content, if they don't match that rule, the current error message is:

"The field XXXXX must match the regular expression '^(19|20)\d{2}$'."

As admin, I want to define a custom error message when defining the property attributes, eg:

"This field must be a year between 1900 and 2100"