Use the env binary to figure out the correct bash to use.
Certain systems ships with an ancient version of bash, but the
user might have installed a newer one that is earlier in $PATH.
For example the current version of Mac OS X ships version 3.2.51
of bash, which does not understand new fancy builtins such as
readarray. A user might install a newer version of bash, use that
as their shell and add that path before bin.
Adds a script that opens the editor to the conflict as part of the merge
process. This way you can fix the merge during the rebase instead of having to
pause the rebase, resolve --mark, rebase --continue.
Only works on unix.
