Fix ENV methods parameter conversion to String

Author: bjfish

CHANGELOG.md

@@ -55,6 +55,7 @@ Bug fixes:
 * Made `Kernel#caller_locations` accept a range argument, and return `nil` when appropriate.
 * Made `rb_respond_to` work with primitives (#1869, @chrisseaton).
 * Fixed issue with missing backtrace for `rescue $ERROR_INFO` (#1660).
+* Fixed parameter conversion to `String` in ENV methods.
 
 Compatibility:
 

spec/tags/core/env/assoc_tags.txt

@@ -1,2 +1 @@
-fails:ENV.index raises TypeError if the argument is not a String and does not respond to #to_str
 fails:ENV.index warns about deprecation