Due to distraction tomb version 1.5 displays its version as 1.4. Also version 1.5 did not work when using -k - to pipe keys from stdin, plus left the encrypted keys laying around in RAM (tmpfs). This was a minor vulnerability fixed in 1.5.1.
Due to an error in the creation and decoding of key files, release versions 1.3 and 1.3.1 cannot open older tombs, plus the tombs created with them will not be opened with older and newer versions of Tomb.
This bug was fixed in commit 551a7839f500a9ba4b26cd63774019d91615cb16
Those who have created tombs with older versions can simply upgrade to release 1.4 (and any other following release) to fix this issue and be able to operate their tombs normally.
Those who have used Tomb 1.3 or 1.3.1 to create new tombs should use Tomb version 1.3.1 to open them and then migrate the contents into a new tomb created using the latest Tomb version.
This bug was due to a typo in the code which appended a GnuPG status string to the content of keys. All users of Tomb 1.3.* should pay particular attention to this issue, however that release series was out as latest for less than a month.