This simplification effort is the result of a (failed) attempt to
micro-optimize this method. I submit it, despite it not being any
faster or slower, because I noticed that the simpler code actually
resulted in behaviours that I consider "less surprising".
* The method previously (I believe, unintentionally) treated all
colons as segment separators. It now only treats double-colon (::)
as segment separator.
Thus "foo.bar:baz" became "foo.bar.baz", now "foo.bar_baz".
* Leading and trailing underscores are no longer removed from
segments. This makes the former-presence of invalid characters
more obvious to consumers and seems helpful.
This also fixed two bugs:
- In some cases, a segment could become the empty string, which is
invalid for Graphite as each segment must be a directory name.
- In some cases, segments could dissappear entirely, thus changing
the hierarchy specified by the producer in ways they probably
didn't expect.
* Avoid use of empty().
Change-Id: I8601faf1fe45124370a92d43e854608e623c1214
143a532b41