Per the bug report, %I results in -'s in the interface name being
replaced with /'s, which means when we try to look up the interface
by path in dhcp-all-interfaces.sh we end up at an invalid path.
Using %i instead should fix the problem.
See https://www.freedesktop.org/software/systemd/man/systemd.unit.html
Essentially what is happening is that we start with a name like
br-ex that wasn't escaped in the first place. However, because of
the - it looks like it could have been escaped to systemd. When
we use %I, which tries to unescape escaped values, it unescapes a
value that was already not escaped.
Change-Id: I434ed2e084d4477dc7a2b7827164586f8ea0c1e3
Closes-Bug: 1649409
d20754f6ed