Well, interestingly clock.t passes but now a different test fails, and sadly it is the same test that fails on the attempted Core Time::HiRes install, stat.t:

~/.cpanm/latest-build/Time-HiRes-1.9758 $ prove -lrv t/stat.t
t/stat.t ..
1..43
# I am the main process 31657, starting the watchdog process...
# The watchdog process 31658 launched, continuing testing...
# I am the watchdog process 31658, sleeping for 360 seconds...
ok 1
ok 2
ok 3
ok 4
ok 5
ok 6
ok 7
ok 8
ok 9
ok 10
ok 11
ok 12
not ok 13

#   Failed test at t/stat.t line 35.
#     Structures begin differing at:
#          $got->[8] = '1525284927'
#     $expected->[8] = '1525284926'
ok 14
ok 15
ok 16
ok 17
ok 18
ok 19
ok 20
ok 21
ok 22
ok 23
ok 24
ok 25
ok 26
ok 27
ok 28
ok 29
ok 30
ok 31
ok 32
ok 33
ok 34
ok 35
# mtime = 1525284926 1525284927 1525284927 1525284927 1525284927
# atime = 1525284926 1525284927 1525284927 1525284927 1525284928
# ai = 4, mi = 4, ss = 0
ok 36 # skip no subsecond timestamps detected
ok 37
ok 38
ok 39
ok 40
ok 41
ok 42
ok 43
# I am the main process 31657, terminating the watchdog process 31658 
+before it terminates me in 358 seconds (testing took 2 seconds).
# kill KILL 31658 = 1
# All done.
# Looks like you failed 1 test of 43.
Dubious, test returned 1 (wstat 256, 0x100)
Failed 1/43 subtests
    (less 1 skipped subtest: 41 okay)

Test Summary Report
-------------------
t/stat.t (Wstat: 256 Tests: 43 Failed: 1)
  Failed test:  13
  Non-zero exit status: 1
Files=1, Tests=43,  2 wallclock secs ( 0.03 usr  0.00 sys +  0.05 cusr
+  0.01 csys =  0.09 CPU)
Result: FAIL
[download]

I guess the only thing left to try is 5.25.9 which according to that thread is patched.