From d72a34311a5a0034659cc0af333d2a9cc09213d6 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Mon, 6 Mar 2017 15:53:34 +0100
Subject: [PATCH] Remove nixFallback

This causes unintended schema upgrades, and is no longer needed now
that we have nixos/modules/installer/tools/nix-fallback-paths.nix.
---
 nixos/default.nix                             |  3 --
 .../modules/installer/tools/nixos-rebuild.sh  | 30 +++++++++----------
 2 files changed, 14 insertions(+), 19 deletions(-)

diff --git a/nixos/default.nix b/nixos/default.nix
index 5f3e2ae081cc..0e45a1cd75e2 100644
--- a/nixos/default.nix
+++ b/nixos/default.nix
@@ -37,7 +37,4 @@ in
   vm = vmConfig.system.build.vm;
 
   vmWithBootLoader = vmWithBootLoaderConfig.system.build.vm;
-
-  # The following are used by nixos-rebuild.
-  nixFallback = pkgs.nixUnstable.out;
 }
diff --git a/nixos/modules/installer/tools/nixos-rebuild.sh b/nixos/modules/installer/tools/nixos-rebuild.sh
index 4f73865dad6a..4b5e7b3230c8 100644
--- a/nixos/modules/installer/tools/nixos-rebuild.sh
+++ b/nixos/modules/installer/tools/nixos-rebuild.sh
@@ -278,24 +278,22 @@ if [ -n "$buildNix" ]; then
     echo "building Nix..." >&2
     nixDrv=
     if ! nixDrv="$(nix-instantiate '<nixpkgs/nixos>' --add-root $tmpDir/nix.drv --indirect -A config.nix.package.out "${extraBuildFlags[@]}")"; then
-        if ! nixDrv="$(nix-instantiate '<nixpkgs/nixos>' --add-root $tmpDir/nix.drv --indirect -A nixFallback "${extraBuildFlags[@]}")"; then
-            if ! nixDrv="$(nix-instantiate '<nixpkgs>' --add-root $tmpDir/nix.drv --indirect -A nix "${extraBuildFlags[@]}")"; then
-                nixStorePath="$(prebuiltNix "$(uname -m)")"
-                if ! nix-store -r $nixStorePath --add-root $tmpDir/nix --indirect \
-                    --option extra-binary-caches https://cache.nixos.org/; then
+        if ! nixDrv="$(nix-instantiate '<nixpkgs>' --add-root $tmpDir/nix.drv --indirect -A nix "${extraBuildFlags[@]}")"; then
+            nixStorePath="$(prebuiltNix "$(uname -m)")"
+            if ! nix-store -r $nixStorePath --add-root $tmpDir/nix --indirect \
+                --option extra-binary-caches https://cache.nixos.org/; then
+                echo "warning: don't know how to get latest Nix" >&2
+            fi
+            # Older version of nix-store -r don't support --add-root.
+            [ -e $tmpDir/nix ] || ln -sf $nixStorePath $tmpDir/nix
+            if [ -n "$buildHost" ]; then
+                remoteNixStorePath="$(prebuiltNix "$(buildHostCmd uname -m)")"
+                remoteNix="$remoteNixStorePath/bin"
+                if ! buildHostCmd nix-store -r $remoteNixStorePath \
+                  --option extra-binary-caches https://cache.nixos.org/ >/dev/null; then
+                    remoteNix=
                     echo "warning: don't know how to get latest Nix" >&2
                 fi
-                # Older version of nix-store -r don't support --add-root.
-                [ -e $tmpDir/nix ] || ln -sf $nixStorePath $tmpDir/nix
-                if [ -n "$buildHost" ]; then
-                    remoteNixStorePath="$(prebuiltNix "$(buildHostCmd uname -m)")"
-                    remoteNix="$remoteNixStorePath/bin"
-                    if ! buildHostCmd nix-store -r $remoteNixStorePath \
-                      --option extra-binary-caches https://cache.nixos.org/ >/dev/null; then
-                        remoteNix=
-                        echo "warning: don't know how to get latest Nix" >&2
-                    fi
-                fi
             fi
         fi
     fi