feat(busybox): set CONFIG_BASH_IS_ASH

[Thrilleratplay]

enable CONFIG_BASH_IS_ASH

Part of #885 and should be included with #900

[tlaurion]

@Thrilleratplay : impact?

[tlaurion]

https://www.in-ulm.de/~mascheck/various/ash/#busybox :

compile time option ("ASH_BASH_COMPAT", active per default) for several bash compatibility features:
option pipefail, substring and replacement parameter expansion ${x:y:z} and ${x/y/z}, [[, source, $'...', &>

[Thrilleratplay]

@tlaurion From everything I can determine, no impact. This seems to only creates a symlink from /bin/ash to /bin/bash. CONFIG_ASH_BASH_COMPAT is a different config, providing Bash like comparability in Ash, and is already enabled. It is because CONFIG_ASH_BASH_COMPAT is enabled that CONFIG_BASH_IS_ASH has no impact. Allowing scripts with shebangs #!/bin/bash to be used in initrd scripts and making shellcheck, which does not have ash compatibility, usable. What I cannot determine is how Bash comparable CONFIG_ASH_BASH_COMPAT is or if there are any limitations. It seems to be improving in newer busybox releases and did not have any issues when converting the scripts shebang to bash in #872.

No...this isn't confusing. Why would you say something like that?

[tlaurion]

@Thrilleratplay haha!