[Apt-listbugs-commits] [SCM] apt-listbugs development tree branch, master, updated. apt-listbugs/0.1.5-8-gbd98100

[Francesco Poli (wintermute)]

The following commit has been merged in the master branch:
commit 9e84883457b31dc17e8ef24c1cfda32b1ce0e8cd
Author: Francesco Poli (wintermute) <invernomuto at paranoici.org>
Date:   Sun Oct 30 23:59:09 2011 +0100

    add explanation about the "affects" field

diff --git a/debian/README.Debian b/debian/README.Debian
index 3dd9397..b11388d 100644
--- a/debian/README.Debian
+++ b/debian/README.Debian
@@ -124,6 +124,68 @@ since *anything* could be included (even by mistake) in the
 APT_LISTBUGS_OPTS environment variable.
 
 
+Why does apt-listbugs ignore the "affects" field?
+=================================================
+
+Sometimes a bug has an effect on package A, but is actually due to
+a flaw in package B. The BTS is able to track this kind of situation:
+the bug report should be assigned to package B (where the bug can
+actually be fixed), but marked as affecting package A, by using the
+"affects" BTS command.
+Nonetheless, apt-listbugs currently ignores the "affects" field.
+In other words, when examining the bugs of package A, apt-listbugs
+does not take bugs affecting A into account: it only looks at the bugs
+actually assigned to A.
+This is intentional, for the reasons explained below.
+
+When a bug is assigned to package B, and found in version b1, but
+marked as affecting package A, this may correspond to one of two
+possible scenarios:
+
+ 0) the bug is actually present in B/b1, but causes breakage in
+    package A, hence, do not upgrade to B/b1, if you want to avoid
+    breaking package A
+ 
+ 1) the bug is actually present in B/b1, but only shows up when a
+    given version (say, a1) of package A is installed, hence, do not
+    upgrade to A/a1, if you want to prevent the bug in package B from
+    showing up
+
+In scenario 0, we should not stop an upgrade (or an installation) of
+package A because of the bug that affects A: package B is the only one
+which is able to introduce the bug into a system. Hence, as long as the
+bug is correctly assigned to B and marked as found in version b1,
+apt-listbugs will give users the opportunity to stop an upgrade to B/b1,
+but, on the other hand, will ignore the bug when upgrading package A.
+This is obtained by ignoring the "affects" field, which is exactly
+what apt-listbugs does.
+
+In scenario 1, stopping an upgrade to A/a1 would actually be useful,
+as it would prevent the bug from showing up. However, the "affects"
+field does not carry any version tracking information, unfortunately.
+This means that there's no way for apt-listbugs to know that the
+problematic upgrade is the one to A/a1, rather than to A/a2 or to
+A/a3. And there's no way for apt-listbugs to distinguish between
+scenario 0 and scenario 1, either. Hence, apt-listbugs currently
+ignores the "affects" field in any case.
+
+Everything said so far holds for the apt-listbugs "apt" command.
+The other apt-listbugs commands ("list" and "rss") should behave
+consistently, or otherwise they will produce misleading output.
+
+Please note that scenario 1 could be dealt with differently, if
+the BTS added version tracking info for the "affects" field,
+or, maybe, if it implemented a distinct way to express scenario 1,
+so that it's not confused with scenario 0 and has version tracking
+info. See
+http://lists.debian.org/debian-devel/2011/10/msg00446.html
+http://lists.debian.org/debian-devel/2011/10/msg00502.html
+for more details.
+If there's consensus on this idea, a wishlist bug report should
+probably be filed against the debbugs package, requesting this
+new feature.
+
+
 Filing Bugs on apt-listbugs
 ===========================
 
diff --git a/debian/changelog b/debian/changelog
index 1853bd0..56ca323 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -12,8 +12,10 @@ apt-listbugs (0.1.6) UNRELEASED; urgency=low
   * modified the querybts invocation to force the text interface,
     when querying a given bug report (apt-listbugs should be able to
     work without access to any X display)
+  * updated README.Debian file: added an explanation of why apt-listbugs
+    currently ignores the "affects" BTS field
 
- -- Francesco Poli (wintermute) <invernomuto at paranoici.org>  Tue, 25 Oct 2011 00:00:59 +0200
+ -- Francesco Poli (wintermute) <invernomuto at paranoici.org>  Sun, 30 Oct 2011 23:53:30 +0100
 
 apt-listbugs (0.1.5) unstable; urgency=low
 

-- 
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