[ruby/irb] Improve how command calls' return value is handled

(https://github.com/ruby/irb/pull/972)

In #934, we changed command calls to return nil only. This PR improves
the behaviour even further by:

- Not echoing the `nil` returned by command calls
- Not overriding previous return value stored in `_` with the
  `nil` from commands

https://github.com/ruby/irb/commit/c844176842

2 files changed, 1 insertions, 2 deletions

diff --git a/lib/irb/context.rb b/lib/irb/context.rb
index aafce7aade..74a08ca694 100644
--- a/lib/irb/context.rb
+++ b/lib/irb/context.rb
@@ -602,7 +602,6 @@ module IRB
         set_last_value(result)
       when Statement::Command
         statement.command_class.execute(self, statement.arg)
-        set_last_value(nil)
       end
 
       nil
diff --git a/lib/irb/statement.rb b/lib/irb/statement.rb
index a3391c12a3..9591a40357 100644
--- a/lib/irb/statement.rb
+++ b/lib/irb/statement.rb
@@ -68,7 +68,7 @@ module IRB
       end
 
       def suppresses_echo?
-        false
+        true
       end
 
       def should_be_handled_by_debugger?