Failing tests in ruby since 1.8.2

The following tests have been failing in Ruby for a long time, including
through today's snapshot:

 1) Failure:
test_delete(TestDBM) [./dbm/test_dbm.rb:332]:
<DBMError> exception expected but none was thrown.

  2) Failure:
test_delete(TestGDBM) [./gdbm/test_gdbm.rb:441]:
<GDBMError> exception expected but none was thrown.

  3) Failure:
test_s_open_error(TestGDBM) [./gdbm/test_gdbm.rb:199]:
<Errno::EACCES> exception expected but was
Class: <Errno::EAGAIN>
Message: <"Resource temporarily unavailable - tmptest_gdbm">
---Backtrace---
./gdbm/test_gdbm.rb:200:in `open'
./gdbm/test_gdbm.rb:200:in `test_s_open_error'
./gdbm/test_gdbm.rb:199:in `test_s_open_error'
---------------

  4) Failure:
test_s_open_error(TestSDBM) [./sdbm/test_sdbm.rb:122]:
<Errno::EACCES> exception expected but none was thrown.


It seems as though, at least for #1,2,4, they fail because they're testing
for a write to a read-only file, but if run as root the write succeeds. 
Obviously you could say "don't run as root", which is feasible but our
automated build process runs as a priviledged user capable of writing to
the tmp directory which is what is causing these to fail.

Is there an easy fix for this?

Caleb