merged usr: Be more careful to distinguish between usrmerge and merged /usr

Merged /usr is a system design, and usrmerge is one implementation of
that design. If we were to de-support merged /usr, it would affect all
users with a merged /usr equally, regardless of how they got there.

diff --git a/914897_merged_usr/ballot.md b/914897_merged_usr/ballot.md
index 11d8da181a9d9bf452b8f3ad5c9c015a90f0c832..3292e9218f4b9c422abba9b73bb4998f66079fa5 100644 (file)
--- a/914897_merged_usr/ballot.md
+++ b/914897_merged_usr/ballot.md
@@ -26,13 +26,15 @@ The compatibility symbolic links `/lib` → `/usr/lib` and `/lib64` → `/usr/li
 
 ## "merged `/usr`" in Debian
 
-In Debian buster, the current testing suite, "merged `/usr`" is only considered for implementation with symlinks (there are no proposals for simply dropping `/{bin,sbin,lib*}`) and is implemented in two distinct ways:
+In Debian buster, the current testing suite, "merged `/usr`" is only considered for implementation with symlinks (there are no proposals for simply dropping `/{bin,sbin,lib*}`) and is implemented in two main ways:
 
 * existing hosts can be made to have a "merged `/usr`" by installing the [usrmerge][2] package;
 * new hosts get the `/{bin,sbin,lib*}/`→ `/usr/{bin,sbin,lib*}/` symlinks by default when using debootstrap >= 1.0.102.
 
 The usrmerge package contains a `/usr/lib/convert-usrmerge` perl executable that runs in `postinst`, that will move the contents of `/{bin,sbin,lib*}/` and replace these directories with symlinks when empty.
 
+It is also possible to merge `/usr` in other ways, for example with `debootstrap --merged-usr` or by bootstrapping into a chroot that already contains the necessary symlinks.
+
 [2]: https://tracker.debian.org/pkg/usrmerge
 
 ## Issues from "merged `/usr`"
@@ -80,7 +82,7 @@ It can be summarized by the following table:
 Given that hosts with different top-level directory schemes already exist; there are various ways forward that would allow for Debian to converge to a desireable situation:
 
 * Flag-day to get all hosts on "merged `/usr`", through a base-files version; probably in buster+1 (bullseye)
-* Disallow "merged `/usr`", let users who ran `usrmerge` on their own
+* Disallow "merged `/usr`", leave users who already have merged `/usr` in an unsupported situation
 * Let Debian converge to a situation where non-"merged `/usr`" Debian hosts are equivalent to symlinked "merged `/usr`" hosts; do this through upgrading all packages shipping files outside of /usr (but exceptions) to stop doing this. Could be achieved by setting policy for buster+1 (should) and buster+2 (must), or maybe even shorter. This would make the symlink "shortcut" migration redundant.
 * Support both "merged `/usr`" and non-"merged `/usr`" systems forever: this implies that our packaging tools need to either support countering effects of "merged `/usr`" (e.g. through manipulating PATH for builds to detect files only in their .deb paths) or identifying tainted packages, and letting installing users decide (warn or error out at install time).