Tests fail because of /tmp mismatch

[eserte]

On most of my smokers the test suite fails like this:

#   Failed test 'Creating file'
#   at t/01-proxy-proc-safeexec.t line 137.
#                   '/var/tmp/cpansmoker-1023/2023091111/p_xnVtvX7k/C4ySPdMbhP'
#     doesn't match '(?^:/tmp/\w+/\w+)'
# Looks like you planned 23 tests but ran 24.
# Looks like you failed 1 test of 24 run.
t/01-proxy-proc-safeexec.t ...... 
Dubious, test returned 1 (wstat 256, 0x100)
Failed 1/23 subtests 

Probably this happens because a different temporary directory is set here, something like TMPDIR=var/tmp/cpansmoker-1023/2023091111.