diff --git a/layout/tools/reftest/runreftest.py b/layout/tools/reftest/runreftest.py
index d5163b197cb..5a1cd3fd89d 100644
--- a/layout/tools/reftest/runreftest.py
+++ b/layout/tools/reftest/runreftest.py
@@ -221,9 +221,6 @@ class RefTest(object):
     # And for about:newtab content fetch and pings.
     prefs['browser.newtabpage.directory.source'] = 'data:application/json,{"reftest":1}'
     prefs['browser.newtabpage.directory.ping'] = ''
-    # Only allow add-ons from the profile and app and allow foreign injection
-    prefs["extensions.enabledScopes"] = 5;
-    prefs["extensions.autoDisableScopes"] = 0;
     # Allow unsigned add-ons
     prefs['xpinstall.signatures.required'] = False
 
diff --git a/testing/profiles/prefs_general.js b/testing/profiles/prefs_general.js
index 8ec90c01762..029854cc6b7 100644
--- a/testing/profiles/prefs_general.js
+++ b/testing/profiles/prefs_general.js
@@ -69,7 +69,6 @@ user_pref("experiments.manifest.uri", "http://%(server)s/experiments-dummy/manif
 // Only load extensions from the application and user profile
 // AddonManager.SCOPE_PROFILE + AddonManager.SCOPE_APPLICATION
 user_pref("extensions.enabledScopes", 5);
-user_pref("extensions.autoDisableScopes", 0);
 // Disable metadata caching for installed add-ons by default
 user_pref("extensions.getAddons.cache.enabled", false);
 // Disable intalling any distribution add-ons
diff --git a/toolkit/mozapps/extensions/internal/XPIProvider.jsm b/toolkit/mozapps/extensions/internal/XPIProvider.jsm
index 258d413644f..c554e6c5be8 100644
--- a/toolkit/mozapps/extensions/internal/XPIProvider.jsm
+++ b/toolkit/mozapps/extensions/internal/XPIProvider.jsm
@@ -657,12 +657,8 @@ function isUsableAddon(aAddon) {
   if (aAddon.type == "theme" && aAddon.internalName == XPIProvider.defaultSkin)
     return true;
 
-  if (mustSign(aAddon.type)) {
-    if (aAddon.signedState <= AddonManager.SIGNEDSTATE_MISSING)
-      return false;
-    if (aAddon.foreignInstall && aAddon.signedState < AddonManager.SIGNEDSTATE_SIGNED)
-      return false;
-  }
+  if (mustSign(aAddon.type) && aAddon.signedState <= AddonManager.SIGNEDSTATE_MISSING)
+    return false;
 
   if (aAddon.blocklistState == Blocklist.STATE_BLOCKED)
     return false;
@@ -2756,12 +2752,9 @@ this.XPIProvider = {
 
         let jsonfile = stagingDir.clone();
         jsonfile.append(id + ".json");
-        // Assume this was a foreign install if there is no cached metadata file
-        let foreignInstall = !jsonfile.exists();
-        let addon;
 
         try {
-          addon = syncLoadManifestFromFile(stageDirEntry);
+          aManifests[aLocation.name][id] = syncLoadManifestFromFile(stageDirEntry);
         }
         catch (e) {
           logger.error("Unable to read add-on manifest from " + stageDirEntry.path, e);
@@ -2771,9 +2764,9 @@ this.XPIProvider = {
           continue;
         }
 
-        if (mustSign(addon.type) &&
-            (addon.signedState <= AddonManager.SIGNEDSTATE_MISSING ||
-            (foreignInstall && addon.signedState < AddonManager.SIGNEDSTATE_SIGNED))) {
+        let addon = aManifests[aLocation.name][id];
+
+        if ((addon.signedState <= AddonManager.SIGNEDSTATE_MISSING) && mustSign(addon.type)) {
           logger.warn("Refusing to install staged add-on " + id + " with signed state " + addon.signedState);
           seenFiles.push(stageDirEntry.leafName);
           seenFiles.push(jsonfile.leafName);
@@ -2782,7 +2775,7 @@ this.XPIProvider = {
 
         // Check for a cached metadata for this add-on, it may contain updated
         // compatibility information
-        if (!foreignInstall) {
+        if (jsonfile.exists()) {
           logger.debug("Found updated metadata for " + id + " in " + aLocation.name);
           let fis = Cc["@mozilla.org/network/file-input-stream;1"].
                        createInstance(Ci.nsIFileInputStream);
@@ -2793,10 +2786,6 @@ this.XPIProvider = {
             fis.init(jsonfile, -1, 0, 0);
             let metadata = json.decodeFromStream(fis, jsonfile.fileSize);
             addon.importMetadata(metadata);
-
-            // Pass this through to addMetadata so it knows this add-on was
-            // likely installed through the UI
-            aManifests[aLocation.name][id] = addon;
           }
           catch (e) {
             // If some data can't be recovered from the cached metadata then it
@@ -3392,9 +3381,6 @@ this.XPIProvider = {
       newAddon.updateDate = aAddonState.mtime;
       newAddon.foreignInstall = isDetectedInstall;
 
-      // appDisabled depends on whether the add-on is a foreignInstall so update
-      newAddon.appDisabled = !isUsableAddon(newAddon);
-
       if (aMigrateData) {
         // If there is migration data then apply it.
         logger.debug("Migrating data from old database");
diff --git a/toolkit/mozapps/extensions/test/xpcshell/test_signed_inject.js b/toolkit/mozapps/extensions/test/xpcshell/test_signed_inject.js
index 302cdd233d6..180661cd255 100644
--- a/toolkit/mozapps/extensions/test/xpcshell/test_signed_inject.js
+++ b/toolkit/mozapps/extensions/test/xpcshell/test_signed_inject.js
@@ -9,7 +9,6 @@ const ADDONS = {
     unsigned: "unsigned_bootstrap_2.xpi",
     badid: "signed_bootstrap_badid_2.xpi",
     signed: "signed_bootstrap_2.xpi",
-    preliminary: "preliminary_bootstrap_2.xpi",
   },
   nonbootstrap: {
     unsigned: "unsigned_nonbootstrap_2.xpi",
@@ -335,45 +334,3 @@ add_task(function*() {
   yield promiseShutdownManager();
   resetPrefs();
 });
-
-// Only fully-signed sideloaded add-ons should work
-add_task(function*() {
-  let file = manuallyInstall(do_get_file(DATA + ADDONS.bootstrap.preliminary), profileDir, ID);
-
-  startupManager();
-
-  // Currently we leave the sideloaded add-on there but just don't run it
-  let addon = yield promiseAddonByID(ID);
-  do_check_neq(addon, null);
-  do_check_true(addon.appDisabled);
-  do_check_false(addon.isActive);
-  do_check_eq(addon.signedState, AddonManager.SIGNEDSTATE_PRELIMINARY);
-  do_check_eq(getActiveVersion(), -1);
-
-  addon.uninstall();
-  yield promiseShutdownManager();
-  resetPrefs();
-
-  do_check_false(file.exists());
-  clearCache(file);
-});
-
-add_task(function*() {
-  let stage = profileDir.clone();
-  stage.append("staged");
-
-  let file = manuallyInstall(do_get_file(DATA + ADDONS.bootstrap.preliminary), stage, ID);
-
-  startupManager();
-
-  // Should have refused to install preliminarily signed version
-  let addon = yield promiseAddonByID(ID);
-  do_check_eq(addon, null);
-  do_check_eq(getActiveVersion(), -1);
-
-  do_check_false(file.exists());
-  clearCache(file);
-
-  yield promiseShutdownManager();
-  resetPrefs();
-});