Avoid setting Exception#cause to itself.

brixen · brixen · commit 2026c0a81dac · 2016-07-19T16:55:00.000-07:00
diff --git a/core/zed.rb b/core/zed.rb
@@ -1431,7 +1431,7 @@ def raise(exc=undefined, msg=undefined, ctx=nil, cause: nil)
     if undefined.equal? exc
       exc = $!
       exc = RuntimeError.new("No current exception") unless exc
-      exc.cause = cause unless exc.cause
+      exc.cause = cause unless exc.cause or exc == cause
     else
       if exc.respond_to? :exception
         if undefined.equal? msg
@@ -1446,8 +1446,8 @@ def raise(exc=undefined, msg=undefined, ctx=nil, cause: nil)
         raise ::TypeError, 'exception class/object expected'
       end
 
-      exc.cause = cause unless exc.cause
-      exc.cause = $! unless exc.cause
+      exc.cause = cause unless exc.cause or exc == cause
+      exc.cause = $! unless exc.cause or exc == $!
     end
 
     if ctx.kind_of? Array
