When tmux is built from a non-release Git version, its version number is
"next-X" where X appears to be the expected version number for the next
release. For example, when built from the current state of master, running
"tmux -V" yields:
tmux next-2.9
Currently check_tmux_pane_size only checks for the version being less than
1.9, so it seems unfair to fail with an obscure Python error in this case.
Let's just use the version number after the "next-" prefix if it is
present.
Signed-off-by: Mike Crowe <mac@mcrowe.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
