Prevent unnecessary installation of bash if bash. Same goes for dash.

diff --git a/modules.d/00dash/install b/modules.d/00dash/install
index 5bf7ae6..0b344ca 100755
--- a/modules.d/00dash/install
+++ b/modules.d/00dash/install
@@ -1,3 +1,6 @@
 #!/bin/bash
+# If another shell is already installed, do not use dash
+[ -x "${initdir}/bin/sh" ] && return
+
 # Prefer dash as /bin/sh if it is available.
 inst /bin/dash && ln -sf dash "${initdir}/bin/sh"
diff --git a/modules.d/99base/install b/modules.d/99base/install
index ce1e2f9..a99f6ab 100755
--- a/modules.d/99base/install
+++ b/modules.d/99base/install
@@ -1,6 +1,9 @@
 #!/bin/bash
-dracut_install mount mknod mkdir modprobe pidof sleep chroot echo sed bash ls flock 
-[ -e "${initdir}/bin/sh" ] || (ln -s bash "${initdir}/bin/sh" || :)
+dracut_install mount mknod mkdir modprobe pidof sleep chroot echo sed ls flock 
+if [ ! -e "${initdir}/bin/sh" ]; then
+    dracut_install bash
+    (ln -s bash "${initdir}/bin/sh" || :)
+fi
 # install our scripts and hooks
 inst "$moddir/init" "/init"
 # Bail out if switch_root does not exist