bazel: substitute the perl path for bash completions

pkgs/development/tools/build-managers/bazel/default.nix

@@ -1,6 +1,6 @@
 { stdenv, lib, fetchurl, runCommand, makeWrapper
 , jdk, zip, unzip, bash, writeCBin, coreutils
-, which, python, gnused, gnugrep, findutils
+, which, python, perl, gnused, gnugrep, findutils
 # Always assume all markers valid (don't redownload dependencies).
 # Also, don't clean up environment variables.
 , enableNixHacks ? false
@@ -139,6 +139,11 @@ stdenv.mkDerivation rec {
       cat tools/bash/runfiles/runfiles.bash >> runfiles.bash.tmp
       mv runfiles.bash.tmp tools/bash/runfiles/runfiles.bash
 
+      # the bash completion requires perl
+      # https://github.com/bazelbuild/bazel/issues/5943
+      substituteInPlace scripts/bazel-complete-template.bash \
+        --replace "perl" "${perl}/bin/perl"
+
       patchShebangs .
     '';
     in lib.optionalString stdenv.hostPlatform.isDarwin darwinPatches