Haus and I looked at this together and it's not the `File.open` that's the problem, but rather the comparison of raw data inside of a string Ruby thinks is encoded as UTF-8 being compared against a regular expression that is also UTF-8.  When this happens the invalid UTF-8 sequence in the raw data causes the exception.

I think we can filter the raw data and make this work in a general way if we do this:

```ruby
txt = File.open("/proc/self/status", "rb").read
txt.encode!('UTF-8', 'UTF-8', :invalid => :replace)
return true if txt =~ /^(s_context|VxID):[[:blank:]]*[0-9]/
```