Sourcetree crashes with orphan branch

For building purposes we create an orphan build branch which basiclly mirrors a corresponding branch, ie;

• master vs. build/master
• some-branch vs. build/some-branch

The branches under build/* are orphan branches. We're doing this via CLI like so;

if build branch exists then
  git clone source/ build/
  git checkout --orphan build/master build/
else
  git branch build/master origin/build/master
  git clone -b build/master source/ build/
endif

The sourcetree GUI sometimes crashes when selecting/viewing a commit from an orphan branch.

The changesets in build/* can get pretty large