So, two of the patches I created for Tracker have been committed
(commit 1, 2)!
I consumed much info (and time) during the process, which entailed
looking at Git usage (branch, checkout, commit, format-patch, ...)
through Philip van Hoof's guidance.
Philip van Hoof also fixed a hard-to-reproduce bug which was a pain
for me. The fix is a workaround for a GTK+ bug.