* Add an alias with a deprecation warning for `nxproxy` to avoid an
immediate breaking change.
* Use the default shell used in the build environment (`stdenv.shell`)
for patching. This shell is in the environment and thus used to patch
scripts using `patchShebangs`. The shell is referenced as `stdenv.shell`
in Makefiles to patch the remaining occurrences of `/bin/bash` in the
build environment.
