This is OpenBSD with OpenSSL. There are no patches for dovecot version 2.3.10.1:

https://github.com/openbsd/ports/tree/master/mail/dovecot/patches 

My latest run is attached. 

> make check

...

Making check in lib-ssl-iostream

make  check-local

for bin in test-iostream-ssl; do  if !  ./$bin; then exit 1; fi;  done

test-common.c:195: Assert failed: suppress == TRUE

Error: server: SSL_accept() syscall failed: Invalid argument

ssl: handshake ....................................................... : FAILED

Panic: file ostream.c: line 54 (o_stream_close_full): assertion failed: (stream->real_stream->error_handling_disabled)

Abort trap (core dumped)

*** Error 1 in src/lib-ssl-iostream (Makefile:919 'check-local')

*** Error 2 in src/lib-ssl-iostream (Makefile:786 'check-am')

*** Error 1 in src (Makefile:588 'check-recursive': @fail=;  if (target_option=k; case ${target_option-} in  ?) ;;  *) echo "am__make_runnin...)

*** Error 1 in /opt/src/dovecot-2.3.10.1 (Makefile:706 'check-recursive': @fail=;  if (target_option=k; case ${target_option-} in  ?) ;;  *)...)

> cd /opt/src/dovecot-2.3.10.1/src/auth

> ./test-libpassword

password scheme(PLAIN) ............................................... : ok

test-libpassword.c:48: Assert failed: password_verify(plaintext, &params, scheme, raw_password, siz, &error) == 1

password scheme(CRYPT) ............................................... : FAILED

password scheme(PLAIN-MD4) ........................................... : ok

password scheme(MD5) ................................................. : ok

password scheme(SHA1) ................................................ : ok

...

1 / 25 tests failed