Calling it only once means that files are read and written only once too.
Total time it takes to run it on the actual fdroiddata dropped from ~25sec to
~6sec.
For git repos, using https:// reduces metadata leakage for more privacy,
and increases the security a little bit. For SVN repos, using https:// is
much more important since the repo format itself does not provide the same
level of verification as git, hg, etc. do.
