Add spec to make sure unexpected signals are not restored to DEFAULT

spec/commands/exec_spec.rb

@@ -723,6 +723,24 @@ def bin_path(a,b,c)
         expect(out).to eq("foo")
       end
     end
+
+    context "signals not being trapped by bunder" do
+      let(:executable) { strip_whitespace <<-RUBY }
+        #{shebang}
+
+        signals = "#{test_signals.join(', ')}".split(', ')
+        result = signals.map do |sig|
+          Signal.trap(sig, "IGNORE")
+        end
+        puts result.select { |ret| ret == "IGNORE" }.count
+      RUBY
+
+      it "makes sure no unexpected signals are restored to DEFAULT" do
+        bundle("exec #{path}")
+
+        expect(out).to eq(test_signals.count.to_s)
+      end
+    end
   end
 
   context "nested bundle exec" do

spec/support/helpers.rb

@@ -217,10 +217,21 @@ def gem_command(command, args = "", options = {})
     end
     bang :gem_command
 
+    def test_signals
+      open3_reserved_signals = %w[CHLD CLD PIPE]
+      reserved_signals = %w[SEGV BUS ILL FPE VTALRM KILL STOP EXIT]
+      bundler_signals = %w[INT]
+
+      Signal.list.keys - (bundler_signals + reserved_signals + open3_reserved_signals)
+    end
+
     def sys_exec(cmd)
       command_execution = CommandExecution.new(cmd.to_s, Dir.pwd)
 
       Open3.popen3(cmd.to_s) do |stdin, stdout, stderr, wait_thr|
+        test_signals.each do |n|
+          Signal.trap(n, "IGNORE")
+        end
         yield stdin, stdout, wait_thr if block_given?
         stdin.close