OS X SourceTree constantly crashing while fetching Gravatar images

SourceTree is neigh on unusable these days (has been for several versions), because it segfaults about once in every 2-10 operations. Operations include:

• Install command line tool (this is super reliable, crashes like 99% of the time when I try this)
• Add file to index
• Commit
• Probably lots of others. It's like just about any time you click the mouse in the UI.

Looking at the crash log, it seems to ALWAYS occur while decoding a JPEG it's fetched over the network or something (see crash file attached)

Using tcpdump/tcpflow and watching the network requests, it looks like the JPEGs in question are being fetched from gravatar.com; when I fetch the URLs manually the JPEGs look just fine, so not sure why it'd be causing the failures.