testsuite: add regression test T25473

mentioned in commit f3bfe26d

mentioned in commit 170dd967

mentioned in commit 6659f50a

mentioned in commit 4c1e63d7

mentioned in commit 34cdad94

mentioned in commit d0562d95

mentioned in commit 17ec5735

mentioned in commit 5fc748be

mentioned in commit bf5b6839

mentioned in commit 470204bc

mentioned in commit c39bb903

mentioned in commit f652ebc4

mentioned in commit ghc/ghc@20d110f1

mentioned in commit f7202822

mentioned in commit 084518d7

mentioned in commit ddb12dff

mentioned in commit d8858ab4

mentioned in commit 6a5c2735

mentioned in commit 2160ac46

mentioned in commit eec4469d

mentioned in commit 2ff92130

mentioned in commit e439f307

mentioned in commit f66b963d

mentioned in commit 4b5ebe66

mentioned in commit bb2c5df3

mentioned in commit 6a075296

mentioned in commit 0d8022d2