Comment 56 for bug 1163886

..and now I can vouch for the veracity of the cache removal. It does indeed reproduce the crash.

If software center is crashing:
 * comment out "self.exhibit_banner.set_exhibits([FeaturedExhibit()])" in lobbyview.py
 * start software center (it runs)
 * stop software center
 * uncomment "self.exhibit_banner.set_exhibits([FeaturedExhibit()])" in lobbyview.py
 * start software center (it runs)
 * stop software center
 * rm ~/.cache/software-center/piston-helper/*
 * start software center (it crashes)

..I'm not sure I did the stack trace correctly. I installed apport-retrace then ran apport-cli and updated the crash report with debug symbols.