guestfs-tools: install bash-completion scripts

pkgs/tools/virtualization/guestfs-tools/default.nix

@@ -1,6 +1,7 @@
 { lib
 , stdenv
 , fetchurl
+, bash-completion
 , bison
 , cdrkit
 , cpio
@@ -56,6 +57,7 @@ stdenv.mkDerivation rec {
   ]);
 
   buildInputs = [
+    bash-completion
     hivex
     jansson
     libguestfs-with-appliance
@@ -74,6 +76,10 @@ stdenv.mkDerivation rec {
     "LIBGUESTFS_PATH=${libguestfs-with-appliance}/lib/guestfs"
   ];
 
+  installFlags = [
+    "BASH_COMPLETIONS_DIR=${placeholder "out"}/share/bash-completion/completions"
+  ];
+
   enableParallelBuilding = true;
 
   postInstall = ''