[[!comment format=mdwn
 username="joey"
 subject="""comment 2"""
 date="2017-01-31T20:24:04Z"
 content="""
The heap profile has multiple spikes (so not an accumulating memory leak).
The diff parsing code is indeed what's using so much memory. Looks like
data is failing to stream through that code and instead the whole
diff output gets buffered.

Aha.. Git.DiffTree.parseDiffRaw used to return a list, but changed
in [[!commit 8d124beba8]]
to a Maybe list in order to avoid being a partial function. But 
that change destroyed laziness, since the whole input has to be parsed
in order to determine if Nothing should be returned.

However, fixing that only eliminated part of the spike. There's something
else keeping data from streaming.
"""]]