Bug#458910: debian-policy: Policy and dpkg disagree on debian revision tests.

[Russ Allbery <rra@debian.org>]

Raphael Hertzog <hertzog@debian.org> writes:

> I confirm that the implementation in dpkg is done in such a way that the
> lack of revision is the same than a revision set to "0".  Exactly like
> the lack of epoch is equal to an epoch of 0.
>
> Maybe we should say "the absence of a debian_revision compares earlier
> than the presence of a non-empty non-null one".

Here is a proposed patch that also clarifies the comparison of version
numbers a bit.  Seconds?

diff --git a/policy.sgml b/policy.sgml
index 1c9a339..b7ac92e 100644
--- a/policy.sgml
+++ b/policy.sgml
@@ -2877,19 +2877,22 @@ Package: libc6
 	          number apart at the last hyphen in the string (if there
 	          is one) to determine the <var>upstream_version</var> and
 	          <var>debian_revision</var>.  The absence of a
-	          <var>debian_revision</var> compares earlier than the
-	          presence of one (but note that the
-	          <var>debian_revision</var> is the least significant part
-	          of the version number).
+	          <var>debian_revision</var> is equivalent to a
+	          <var>debian_revision</var> of <tt>0</tt>.
 	        </p>
 	      </item>
 	    </taglist>
 	  </p>
 
 	  <p>
-	    The <var>upstream_version</var> and <var>debian_revision</var>
+	    When comparing two version numbers, first the <var>epoch</var>
+	    of each are compared, then the <var>upstream_version</var> if
+	    <var>epoch</var> is equal, and then <var>debian_revision</var>
+	    if <var>upstream_version</var> is also equal.
+	    <var>epoch</var> is compared numerically.  The
+	    <var>upstream_version</var> and <var>debian_revision</var>
 	    parts are compared by the package management system using the
-	    same algorithm:
+	    following algorithm:
 	  </p>
 
 	  <p>

-- 
Russ Allbery (rra@debian.org)               <http://www.eyrie.org/~eagle/>