after `make test` /dev/null is owned by root

when I ran `make test`
I have been asked password of current user.
```
$ make test
Running tests...
Test project /home/dev/git/bcc/build
Start 1: style-check
1/42 Test #1: style-check ...................... Passed 0.97 sec
Start 2: c_test_static
[sudo] password for dev:
2/42 Test #2: c_test_static .................... Passed 7.03 sec
Start 3: test_libbcc
```
I noticed this change of ownership because my tab completion stopped working with error

`bash: /dev/null: Permission denied`

I am trying to find root cause I am sure its in test case `c_test_static`

Any help or suggestion or pointers are welcome.

Reproduce the problem with `make test` and focus first on the `c_test_static` test, where the password prompt appears. Trace how that test handles `/dev/null` and verify that a completed test leaves `/dev/null` accessible to the current user without changing its ownership.

Written by the indexing model from the issue text.