extensions: include current version in "invalid version" message
It is "not so rare" for the mercurial version to be badly detected at build
time. In such case, version check for extensions gets confused.
To help pinpoint the error, we now include the Mercurial's version number in
the error message.
public attribute not declared in interfaces: badpeer.badattribute
public attribute not declared in interfaces: badpeer.badmethod