Screwy Fetch Behavior

[Fred Wright]

A while back, I noticed that MacPorts was sometimes trying to fetch patch 
files from distfile mirrors.  At the time, it only applied to some ports 
that I keep privately modified, so it was just in the "should look into 
this some time" category.  But now it's biting me in attempting to update 
the ntpsec port.  As usual, I started by just updating the version number 
in the Portfile and doing a "sudo port fetch" (to check the fetch and then 
check the signature on the resulting file).  But it now (unsuccessfully) 
attempts to fetch the patchfile from the distfile mirrors, and then gives 
up without fetching the real distfile at all.  I don't think base has 
changed since the last time I successfully did this, so perhaps there's 
something in the ports tree that changed the fetch behavior.

I don't know if this only applies to locally modified portfiles or not, 
but even if it does, it blocks updating the port.  What's causing this and 
how do I get around it?

Fred Wright