portupgrade spurious skips

[Nate Eldredge]

Hi folks,

In the past few months I've noticed a bug in portupgrade.  When I update 
my ports tree and do `portupgrade -a', often a few ports will be skipped, 
supposedly because another port on which they depend failed to install. 
However, the apparently failed port actually did not fail, and if I rerun 
`portupgrade -a', some of the skipped ports will install successfully 
without complaint.  After enough iterations I can eventually get all of 
them.

I'd like to file a PR about this, but it's a little bit tricky coming up 
with a test case, since the behavior depends on having outdated packages 
installed, and on the dependencies between them.  Moreover, after I run 
`portupgrade -a' and notice the problem, the state of the installed 
packages has changed and the same packages aren't skipped the next time. 
So my question is whether anyone has ideas about how to construct a 
reasonable test case that could help me make this reproducible and easier 
to investigate.  Any thoughts?

Thanks in advance.

-- 

Nate Eldredge
neldredge at math.ucsd.edu