Hmm, I don't know.
Comparing the versions in git shows me three commits, two of which affect building Sigil on OSX
only, and the third updates the text in the credits.
As the Changelog says:
- Update links
- Try to work around clang compiler issues with older C++ cdebase
...
Well, maybe the version of Qt5 it was built against was different. But I'd expect later versions of Sigil to build against later versions of Qt5, which if anything would get rid of bugs...