annoying new bug in movement

[Jim Kingdon <kingdon at panix dot com>]

In the standard game, if I have an infantry in a bomber, and the
infantry tries to move (using a movement key, like "h") out of the
bomber, sometimes it fails.  Control-e (disembark) seems to still
work, but of course that puts me in a different hex than where I
wanted to go.  This is fairly new, probably with the new path code.

By "fails" I mean that the ACP now shows "0/1" but the infantry hasn't
gone anywhere.  It doesn't even go into reserve mode, which I could
recover from.

Unless my work with the debugger was mistaken, I tracked it down to
path_get_next_move returning -1 (although that leaves me with a
followup question: why would the caller burn ACP rather than going
into reserve in that case).

And as for "sometimes", I haven't been able to figure out when and
when not.  Sometimes the bomber is over sea, sometimes land.

I'm not sure what to try next.  The path code is quite complicated....