[mythtv] Note for subscribers to -commits list

[Michael T. Dean]

As some of you may have been filtering messages from the mythtv-commits 
list on the "custom" header X-Branch, I wanted to give you a heads up 
that the new git server uses a different name for the header: 
X-Git-Refname.  The new header name is "standard" with the new server 
setup, so rather than add back the custom one (and have to keep 
remembering to do that with future changes), we'll be sticking to the 
stock configuration/header name.  So, please update your filters 
appropriately.

Examples are shown below:

X-Git-Refname: refs/heads/master

or

X-Git-Refname: refs/heads/fixes/0.25

Mike