Merge pull request #263 from joshtriplett/c-dtor-clarify

C-DTOR: Clarify that `Drop` should ignore errors

src/dependability.md

@@ -81,7 +81,8 @@ destructor causes the program to abort.
 
 Instead of failing in a destructor, provide a separate method for checking for
 clean teardown, e.g. a `close` method, that returns a `Result` to signal
-problems.
+problems. If that `close` method is not called, the `Drop` implementation
+should do the teardown and ignore or log/trace any errors it produces.
 
 
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