Bug#336342: Clarify permitted epoch values

[Florian Weimer <fw@deneb.enyo.de>]

retitle 336342 Clarify permitted epoch values
thanks

* Florian Weimer:

> Package: debian-policy
> Version: 3.6.2.1
> Severity: normal
>
> In section 5.6.12, the permitted epoch values are not specified
> precisely.  Large epochs tend to cause problems for some tools, for
> example dpkg, whose behavior is even architecture-specific.  There
> might be other problems throughout the toolchain.
>
> Maybe Policy should be changed to reflect this, from
>
>   "This is a single (generally small) unsigned integer."
>
> to:
>
>   "This is a single unsigned integer, consisting of at most 8 digits,
>   but it is generally much smaller."

After investigating the situation in APT, I think it might be a good
idea to change this paragraph

     <epoch>
          This is a single (generally small) unsigned integer.  It may be
          omitted, in which case zero is assumed.  If it is omitted then
          the <upstream_version> may not contain any colons.

to

     <epoch>
          This is a positive integer, consisting of at most 8 digits,
          but it is generally much smaller.  It may be omitted (along
          with the following colon), in which case zero is used in the
          comparison described below.  If it is omitted then the
          <upstream_version> may not contain any colons.

This rules out "0:" and ":" (which are handled differently by dpkg and
APT), and forces the value to fit in a 32-bit long (which is required
by dpkg).

(The original title was incorrect, subsequent numeric components are
less ambiguous.)