Use of uninitialized value in fil_crypt_rotate_page

When running mtr --valgrind on all tests I got the following error.
Unfortunately I can't repeat it by just running the one test case

encryption.create_or_replace 'cbc,innodb' w6 [ fail ] Found warnings/errors in
server log file!

==10859== Thread 25:
==10859== Conditional jump or move depends on uninitialised value(s)
==10859== at 0x1542C31: fil_crypt_rotate_page(key_state_t const*, rotate_thread_t*) (fil0crypt.cc:1831)
==10859== by 0x1543193: fil_crypt_rotate_pages(key_state_t const*, rotate_thread_t*) (fil0crypt.cc:1949)
==10859== by 0x1543A1A: fil_crypt_thread (fil0crypt.cc:2143)
==10859== by 0x4E434F8: start_thread (pthread_create.c:465)
==10859== by 0x6F26FBE: clone (clone.S:95)
==10859== Conditional jump or move depends on uninitialised value(s)
==10859== at 0x1542C41: fil_crypt_rotate_page(key_state_t const*, rotate_thread_t*) (fil0crypt.cc:1831)
==10859== by 0x1543193: fil_crypt_rotate_pages(key_state_t const*, rotate_thread_t*) (fil0crypt.cc:1949)
==10859== by 0x1543A1A: fil_crypt_thread (fil0crypt.cc:2143)
==10859== by 0x4E434F8: start_thread (pthread_create.c:465)
==10859== by 0x6F26FBE: clone (clone.S:95)
==10859== Conditional jump or move depends on uninitialised value(s)
==10859== at 0x1542DA6: fil_crypt_rotate_page(key_state_t const*, rotate_thread_t*) (fil0crypt.cc:1892)
==10859== by 0x1543193: fil_crypt_rotate_pages(key_state_t const*, rotate_thread_t*) (fil0crypt.cc:1949)
==10859== by 0x1543A1A: fil_crypt_thread (fil0crypt.cc:2143)
==10859== by 0x4E434F8: start_thread (pthread_create.c:465)
==10859== by 0x6F26FBE: clone (clone.S:95)