exchange: guard against method invocation on `b2caps=None` args
I couldn't figure out how these are called, but the value is pretty obviously
set at least for the cases that have tests.
Differential Revision: https://phab.mercurial-scm.org/D7512
#!/bin/rc
# 9mail - Mercurial email wrapper for upas/marshal
fn usage {
echo >[1=2] usage: mercurial/9mail -f from to [cc]
exit usage
}
from=()
cc=()
to=()
switch($1){
case -f
from=$2
case *
usage
}
to=($3)
if(~ $#* 4)
cc=(-C $4)
upasname=$from
upas/marshal $cc $to