jenkinsci/mercurial-plugin — comment on commit 24c3a797f2feb8d8e1f3994a04e7dd0eabaa9cad
File: src/main/java/hudson/plugins/mercurial/MercurialSCM.java line 238
By willemv:

Don't you always need to enable the share extension, for _every_ hg command ? Otherwise the other hg commands won't be able to find the store of the mercurial history.