RFC: ? Add a warning when matching locale against utf8

We warn people in the pods that it is not a good idea to mix locale and 
utf8.  I propose adding a warning message when it does happen.

What actually goes on in this circumstance is that the actual locale is 
ignored.  If that locale is not ISO 8859-1, then your results are likely 
to be garbage to whatever extent the locale differs from 8859-1.  The 
'A' in your locale may, for example, not be Unicode's 'A'.

Since 8859-1 is a subset of Unicode, that locale will result in 
non-garbage, but you may get unexpected results with characters matching 
outside the locale.

• RFC: ? Add a warning when matching locale against utf8 by karl williamson