We use an interactive shell so that users can use their custom shell aliases in
lazygit's shell prompt, which is convenient; however, this only really works for
shells like bash or zsh. We know it doesn't work for fish or nushell (because
these use different names for the $? variable); so use an interactive shell only
if the user's shell is either bash or zsh.
In 5a3049485c we changed the execution of shell commands to use an interactive
shell (-i), because this allows users to use aliases or shell functions, which
is a nice convenience.
Since then, however, many users have reported problems with lazygit not coming
back to the foreground after executing a shell command. Some users report that
appending "; exit" to the end of the command line solves this. I don't really
understand what the cause of this problem was, or why appending "; exit" solves
it, but if it helps, let's do it.
Also, use the user's shell (from the SHELL env variable) instead of bash. Both
of these together allow users to use their shell aliases or shell functions in
the interactive command prompt.
