user id problem with special characters

[jeanpommier]

j-pommier and j.pommier users in geOrchestra would both be translated as j_pommier in CKAN

geOrchestra and ckan don't enforce the same rules for user id definition.
geOrchestra accepts - and . in the user ID (but not _)
CKAN accepts _ but not - or .
In its current state, this extension translates . and - into _. Which could lead to an id collision.