attempt to fix tests with proguard tweaks

https://stackoverflow.com/questions/5701126/compile-with-proguard-gives-exception-local-variable-type-mismatch

       [dx] local variable type mismatch: attempt to set or access a value of type int using a local variable of type info.guardianproject.libcore.io.ErrnoException. This is symptomatic of .class transformation tools that ignore local variable information.
       [dx]
       [dx] ...at bytecode offset 0000002e
       [dx] locals[0000]: Linfo/guardianproject/iocipher/File;
       [dx] locals[0001]: Linfo/guardianproject/iocipher/FileDescriptor;
       [dx] locals[0002]: <invalid>
       [dx] locals[0003]: <invalid>
       [dx] locals[0004]: <invalid>
       [dx] locals[0005]: [Z
       [dx] stack[top0]: int{0x00000001 / 1}
       [dx] ...while working on block 002c
       [dx] ...while working on method createNewFile:()Z
       [dx] ...while processing createNewFile ()Z
       [dx] ...while processing info/guardianproject/iocipher/File.class
       [dx]
       [dx] 1 error; aborting