Fix the error message when a command fails in the build process

Author: kateinoigakukun

Rakefile

@@ -71,7 +71,7 @@ class BuildTask < Struct.new(:name, :target, :build_command)
     cmd = build_command + ["--print-ruby-cache-key"]
     stdout, status = Open3.capture2(*cmd)
     unless status.success?
-      raise "Command failed with status (#{status.exitstatus}): #{cmd.join ""}"
+      raise "Command failed with status (#{status.exitstatus}): #{cmd.join " "}"
     end
     require "json"
     @key = JSON.parse(stdout)

rakelib/packaging.rake

@@ -32,7 +32,7 @@ def npm_pkg_rubies_cache_key(pkg)
   chdir = pkg[:gemfile] ? File.dirname(pkg[:gemfile]) : Dir.pwd
   stdout, status = Open3.capture2(*cmd, chdir: chdir)
   unless status.success?
-    raise "Command failed with status (#{status.exitstatus}): #{cmd.join ""}"
+    raise "Command failed with status (#{status.exitstatus}): #{cmd.join " "}"
   end
   require "json"
   JSON.parse(stdout)["hexdigest"]