build-release-notes: ban unprefixed issue numbers

This is necessary to cleanly and unambiguously transition to using
forgejo issues, since we now control our own destiny.

If we ban unprefixed numbers for a couple of releases, we ensure there
are no releases in active support with the wrong unprefixed number
semantics that could receive backports.

Change-Id: I1c94541dcb3f071399f439870b48cd76557b70d2

doc/manual/rl-next/avoid-killing-build-user.md

@@ -1,6 +1,6 @@
 ---
 synopsis: Avoid unnecessarily killing processes for the build user's UID
-issues: [9142, fj#667]
+issues: [nix#9142, fj#667]
 cls: []
 category: Fixes
 credits: [teofilc]

doc/manual/rl-next/filterSource-filter-chroot-stores.md

@@ -1,6 +1,6 @@
 ---
 synopsis: fix usage of `builtins.filterSource` and `builtins.path` with the filter argument when using chroot stores
-issues: [11503]
+issues: [nix#11503]
 credits: [lily, alois31, horrors]
 category: Fixes
 ---

doc/manual/rl-next/nix-instantiate-parse-json.md

@@ -1,6 +1,6 @@
 ---
 synopsis: '`nix-instantiate --parse` outputs json'
-issues: [fj#487, 11124, 4726, 3077]
+issues: [fj#487, nix#11124, nix#4726, nix#3077]
 cls: [2190]
 category: Breaking Changes
 credits: [piegames, horrors]

maintainers/build-release-notes.py

@@ -70,11 +70,17 @@ class AuthorInfoDB:
 def format_link(ident: str, gh_part: str, fj_part: str) -> str:
     # FIXME: deprecate github as default
     if ident.isdigit():
-        num, link, base = int(ident), f"#{ident}", f"{GH_REPO_BASE}/{gh_part}"
+        raise ValueError('Unprefixed issue numbers are disallowed until the Lix 2.95 cycle, when they will become Forgejo references instead of their previous state of CppNix GitHub issues.'
+            '\nIf you mean a Lix Forgejo reference, prefix with fj# or lix#'
+            '\nIf you mean a CppNix issue, prefix the number with gh# or nix#')
     elif ident.startswith("gh#"):
         num, link, base = int(ident[3:]), ident, f"{GH_REPO_BASE}/{gh_part}"
+    elif ident.startswith("nix#"):
+        num, link, base = int(ident[4:]), ident, f"{GH_REPO_BASE}/{gh_part}"
     elif ident.startswith("fj#"):
         num, link, base = int(ident[3:]), ident, f"{FORGEJO_REPO_BASE}/{fj_part}"
+    elif ident.startswith("lix#"):
+        num, link, base = int(ident[4:]), ident, f"{FORGEJO_REPO_BASE}/{fj_part}"
     else:
         raise Exception("unrecognized reference format", ident)
     return f"[{link}]({base}/{num})"