Good :)
It's a known problem that sometimes lilypond fails to rebuild and has
to be built from scratch. It's nevertheless surprising that this had
happened to you...
Let me know if you'll have any problems with building other branches.
And btw, since you're going to have several lilyponds with the same
version number, you might be interested in running Frescobaldi from
source as well, since it will enable you to use this enhancement made
by me:
https://github.com/wbsoft/frescobaldi/commit/59f54df181d3d24be79387eaedec3c89faaa4e31