Merge ~ginggs/casper:breaks-lupin-casper into casper:main

[Graham Inggs]

[Steve Langasek (vorlon)]

review: Needs Fixing

[Steve Langasek (vorlon)]

review: Needs Fixing

[Graham Inggs (ginggs)]

xnox and I went over this section of policy [1] before I proposed this MR. I've numbered the use cases below for clarity.

"
Normally, Breaks should be used instead of Conflicts since Conflicts imposes a stronger restriction on the ordering of package installation or upgrade and can make it more difficult for the package manager to find a correct solution to an upgrade or installation problem. Breaks should be used

1. when moving a file from one package to another (see Overwriting files and replacing packages - Replaces),

2. when splitting a package (a special case of the previous one), or

3. when the breaking package exposes a bug in or interacts badly with particular versions of the broken package.

Conflicts should be used

4. when two packages provide the same file and will continue to do so,

5. in conjunction with Provides when only one package providing a given virtual facility can be unpacked at a time (see Virtual packages - Provides),

6. in other cases where one must prevent simultaneous installation of two packages for reasons that are ongoing (not fixed in a later version of one of the packages) or that must prevent both packages from being unpacked at the same time, not just configured.
"

1 is applicable
4 is not applicable since we will not have two package continue to provide the same file
2, 3, 5 and 6 are not applicable

[1] https://www.debian.org/doc/debian-policy/ch-relationships.html#conflicting-binary-packages-conflicts

[Steve Langasek (vorlon)]

On Wed, Apr 20, 2022 at 03:41:29PM -0000, Graham Inggs wrote:
> Conflicts should be used

> 4. when two packages provide the same file and will continue to do so,

I see that the wording in policy allows for this interpretation, because the
other package is going away and therefore will not "continue to" provide the
file.

However, there will never be a version of the package that does NOT provide
the file, because the package itself is dead.

When this part of policy was drafted, I think it was the common
understanding that this referred to the difference between the case where
you wanted to keep both packages installed after upgrade, and the case where
one of the packages would be removed in favor of the other. I have never
seen discussion/analysis of the use of unversioned Breaks suggesting that
this is a good thing to do.

I wouldn't block this, but I still think it's better to use Conflicts
instead of unversioned Breaks here.

[Julian Andres Klode (juliank)]

Since there is a Replaces, this is covered by Policy 7.6.2 which combines them with Conflicts.

Breaks should always be versioned and indicate that the package should be upgraded to a newer version. This should be a Conflicts, if only because we have code $somewhere (I think it's in update-manager?) in Ubuntu that reads Replaces+Conflicts and calculates a list of obsolete package that should be removed.

Alternatively, update-manager could be tweaked to handle unversioned Breaks like Conflicts, but then policy 7.6.2 needs to be updated to allow for Breaks.

review: Needs Fixing

323958c... by Graham Inggs on 2022-04-26

Use Conflicts instead of Breaks, as per review

[Julian Andres Klode (juliank)]

This looks good. For the change to update-manager to handle Replaces with Breaks, see

https://code.launchpad.net/~juliank/update-manager/remove-breaks/+merge/420537

review: Approve

[Steve Langasek (vorlon)]

review: Approve

Unmerged commits

323958c... by Graham Inggs on 2022-04-26

Use Conflicts instead of Breaks, as per review

027d065... by Graham Inggs on 2022-04-20

Add unversioned Breaks, Replaces on lupin-casper (LP: #1969464)

unversioned because lupin was removed and there is no fixed verson,
and Breaks instead of Conflicts because it it easier for dpkg to resolve

diff --git a/debian/changelog b/debian/changelog
index b278f35..04d1af5 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,9 @@
+casper (1.471) UNRELEASED; urgency=medium
+
+  * Add Conflicts, Replaces on lupin-casper (LP: #1969464)
+
+ -- Graham Inggs <[e-mail]>  Tue, 26 Apr 2022 08:05:54 +0000
+
 casper (1.470) jammy; urgency=medium
 
   * Add missing include of casper-helpers, needed by the iso-scan script.
diff --git a/debian/control b/debian/control
index 7464642..5c535ed 100644
--- a/debian/control
+++ b/debian/control
@@ -11,8 +11,9 @@ Architecture: any
 Section: misc
 Priority: extra
 Depends: ${shlibs:Depends}, ${misc:Depends}, initramfs-tools (>= 0.92bubuntu55), busybox-initramfs (>= 1:1.1.3-4ubuntu3), dmsetup, user-setup, sudo, eject, uuid-runtime, localechooser-data (>= 2.65ubuntu1) | ubiquity, util-linux (>= 2.15-1), file, lzma, udev (>= 174), cifs-utils, finalrd, fdisk
-Conflicts: usplash (<< 0.4-43), live-initramfs
+Conflicts: usplash (<< 0.4-43), live-initramfs, lupin-casper
 Breaks: genext2fs (<< 1.4.1)
+Replaces: lupin-casper
 Tag: admin::boot, admin::filesystem, implemented-in::shell, protocol::smb, role::plugin, scope::utility, special::completely-tagged, works-with-format::iso9660
 Description: Run a "live" preinstalled system from read-only media