Mirah run mode should not stop the process unless compile failed

Before, we would exit zero when the main finished. If for example, you are running a swing app, that isn't so hot. Because, swing launches its own event thread
(cherry picked from commit aeace8a)

Author: baroquebobcat

src/org/mirah/mirah_command.mirah

@@ -36,7 +36,9 @@ class MirahCommand
   def self.main(args:String[]):void
     list = Arrays.asList(args)
     if list.size > 0 && "run".equals(list.get(0))
-      System.exit(run(list.subList(1, list.size)))
+      result = run(list.subList(1, list.size))
+      # NB only exit from a run if it failed.
+      System.exit(result) unless result == 0
     elsif list.size > 0 && "compile".equals(list.get(0))
       System.exit(compile(list.subList(1, list.size)))
     else

src/org/mirah/tool/run_command.mirah

@@ -58,7 +58,7 @@ class RunCommand < MirahTool
       main_method.invoke(nil, args)
       0
     else
-      puts "No main method found"
+      puts "Error: No main method found."
       1
     end
   end
@@ -78,7 +78,9 @@ class RunCommand < MirahTool
 
   def self.main(args:String[]):void
     result = run(args)
-    System.exit(result)
+
+    # NB only exit from a run if it failed.
+    System.exit(result) unless result == 0
   end
 
   def self.run(args: String[]): int

test/artifacts/jar_test.rb

@@ -20,4 +20,9 @@ def test_happy_path
   	out = `java -jar dist/mirahc.jar run -e 'puts 1'`
     assert_equal "1\n", out
   end
+
+  def test_run_doesnt_exit_early
+    out = `java -jar dist/mirahc.jar run -e 'Thread.new {Thread.sleep(1); puts 1}.start'`
+    assert_equal "1\n", out
+  end
 end