cherry-pick, revert: add the --gpg-sign option

Signed-off-by: Nicolas Vigier <boklm@mars-attacks.org>
git-sh-setup.sh: add variable to use the stuck-long mode

If the variable $OPTIONS_STUCKLONG is not empty, then rev-parse
option parsing is done in --stuck-long mode.

Signed-off-by: Nicolas Vigier <boklm@mars-attacks.org>
am: parse options in stuck-long mode

There is no functionnal change. The reason for this change is to be able
to add a new option taking an optional argument.

Signed-off-by: Nicolas Vigier <boklm@mars-attacks.org>
am: add the --gpg-sign option

Signed-off-by: Nicolas Vigier <boklm@mars-attacks.org>
rebase: remove useless arguments check

Remove a check on the number of arguments for --onto and -x options.
It is not possible for $# to be <= 2 at this point :

 - if --onto or -x has an argument, git rev-parse --parseopt will
   provide something like this :
     set -- --onto 'x' --
   when parsing the "--onto" option, $# will be 3 or more if there are
   other options.

- if --onto or -x doesn't have an argument, git rev-parse --parseopt
  will exit with an error and display usage information.

Signed-off-by: Nicolas Vigier <boklm@mars-attacks.org>
rebase: parse options in stuck-long mode

There is no functionnal change. The reason for this change is to be able
to add a new option taking an optional argument.

Signed-off-by: Nicolas Vigier <boklm@mars-attacks.org>
rebase: add the --gpg-sign option

Signed-off-by: Nicolas Vigier <boklm@mars-attacks.org>