merge revision(s) 40413,40414,40415,40423: [Backport #8290]

	* string.c (rb_str_inspect): NUL should not be represented as
	  "\0" when octal digits may follow.

	* string.c (rb_str_inspect): NUL should not be represented as "\0"
	  when octal digits may follow.  [ruby-core:54458] [Bug #8290]

	* test/ruby/test_module.rb
	  (TestModule#test_const_get_invalid_name)
	  (test_const_defined_invalid_name): Fix expected values.

	* string.c (rb_str_inspect): refix r40413, on Ruby 1.9 usual character
	  escape uses hex/Unicode escapes, so fix to use Unicode escape on
	  Unicode strings and hex on others. [ruby-core:54458] [Bug #8290]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_0_0@40488 b2dd03c8-39d4-4d8f-98ff-823fe69b080e