Fix error when Encoding.default_external is Encoding::IBM437

https://ci.appveyor.com/project/ruby/ruby/build/1.0.9151#L4601
```
  1) Error:
TestArgf#test_inplace_nonascii:
Encoding::UndefinedConversionError: U+3042 from UTF-8 to IBM437
```

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@64249 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 5 insertions, 5 deletions

diff --git a/test/ruby/test_argf.rb b/test/ruby/test_argf.rb
index 84397a2d01..a76bdccf45 100644
--- a/test/ruby/test_argf.rb
+++ b/test/ruby/test_argf.rb
@@ -258,12 +258,12 @@ class TestArgf < Test::Unit::TestCase
   def test_inplace_nonascii
     ext = Encoding.default_external or
       skip "no default external encoding"
-    if ext == Encoding::US_ASCII
-      skip "external encoding is us-ascii"
-    end
     t = nil
-    ["\u{3042}", "\u{e9}"].any? {|n| t = make_tempfile(n.encode(ext))} or
-      skip "no name to test"
+    ["\u{3042}", "\u{e9}"].any? do |n|
+      t = make_tempfile(n.encode(ext))
+    rescue Encoding::UndefinedConversionError
+    end
+    t or skip "no name to test"
     assert_in_out_err(["-i.bak", "-", t.path],
                       "#{<<~"{#"}\n#{<<~'};'}")
     {#