Error in puppet module install under Puppet 3.6.x: Version numbers MUST begin with three dot-separated numbers

[Aron Roberts]

When running 'puppet module install ...' under Puppet 3.6.x, we encountered the error message:

Error: Version numbers MUST begin with three dot-separated numbers
Error: Try 'puppet help module install' for usage

We eventually tracked this down to a version number that wasn't in the requisite format, in the metadata.json file of an in-house-developed module.  E.g. it was:

"version": "4.1 alpha",

rather than (as now required):

"version": "4.1.0",

Posting this here in case anyone else might run into this.  This validation behavior was *not* present in any other version of Puppet we'd previously used; that is, in version 3.4.3 or earlier.