--- a/config/tests/test_mozbuild_reading.py
+++ b/config/tests/test_mozbuild_reading.py
@@ -77,16 +77,19 @@ class TestMozbuildReading(unittest.TestC
 
         try:
             config = mb.config_environment
         except Exception as e:
             if e.message == 'config.status not available. Run configure.':
                 raise unittest.SkipTest('failing without config.status')
             raise
 
+        if config.substs['MOZ_BUILD_APP'] == 'js':
+            raise unittest.SkipTest('failing in Spidermonkey builds')
+
         reader = BuildReader(config)
         all_paths = self._mozbuilds(reader)
         _, contexts = reader.read_relevant_mozbuilds(all_paths)
 
         finder = FileFinder(config.topsrcdir, find_executables=False,
                             ignore=['obj*'])
 
         def pattern_exists(pat):

--- a/configure.py
+++ b/configure.py
@@ -77,18 +77,17 @@ if __name__ == '__main__':
     from mozbuild.config_status import config_status
     config_status(**args)
 ''')
 
     # Other things than us are going to run this file, so we need to give it
     # executable permissions.
     os.chmod('config.status', 0755)
     if config.get('MOZ_BUILD_APP') != 'js' or config.get('JS_STANDALONE'):
-        if not config.get('JS_STANDALONE'):
-            os.environ['WRITE_MOZINFO'] = '1'
+        os.environ['WRITE_MOZINFO'] = '1'
         # Until we have access to the virtualenv from this script, execute
         # config.status externally, with the virtualenv python.
         return subprocess.call([config['PYTHON'], 'config.status'])
     return 0
 
 
 if __name__ == '__main__':
     sys.exit(main(sys.argv))

--- a/python/mozbuild/mozbuild/mozinfo.py
+++ b/python/mozbuild/mozbuild/mozinfo.py
@@ -15,17 +15,17 @@ import mozbuild.mozconfig as mozconfig
 def build_dict(config, env=os.environ):
     """
     Build a dict containing data about the build configuration from
     the environment.
     """
     substs = config.substs
 
     # Check that all required variables are present first.
-    required = ["TARGET_CPU", "OS_TARGET", "MOZ_WIDGET_TOOLKIT"]
+    required = ["TARGET_CPU", "OS_TARGET"]
     missing = [r for r in required if r not in substs]
     if missing:
         raise Exception("Missing required environment variables: %s" %
                         ', '.join(missing))
 
     d = {}
     d['topsrcdir'] = config.topsrcdir
 
@@ -33,25 +33,25 @@ def build_dict(config, env=os.environ):
     if the_mozconfig:
         d['mozconfig'] = the_mozconfig
 
     # os
     o = substs["OS_TARGET"]
     known_os = {"Linux": "linux",
                 "WINNT": "win",
                 "Darwin": "mac",
-                "Android": "b2g" if substs["MOZ_WIDGET_TOOLKIT"] == "gonk" else "android"}
+                "Android": "b2g" if substs.get("MOZ_WIDGET_TOOLKIT") == "gonk" else "android"}
     if o in known_os:
         d["os"] = known_os[o]
     else:
         # Allow unknown values, just lowercase them.
         d["os"] = o.lower()
 
     # Widget toolkit, just pass the value directly through.
-    d["toolkit"] = substs["MOZ_WIDGET_TOOLKIT"]
+    d["toolkit"] = substs.get("MOZ_WIDGET_TOOLKIT")
 
     # Application name
     if 'MOZ_APP_NAME' in substs:
         d["appname"] = substs["MOZ_APP_NAME"]
 
     # Build app name
     if 'MOZ_MULET' in substs and substs.get('MOZ_MULET') == "1":
         d["buildapp"] = "mulet"

--- a/taskcluster/scripts/builder/hazard-analysis.sh
+++ b/taskcluster/scripts/builder/hazard-analysis.sh
@@ -31,18 +31,20 @@ fi
 
 function build_js_shell () {
     ( cd $JS_SRCDIR; autoconf-2.13 )
     if [[ -z "$HAZ_DEP" ]]; then
         [ -d $HAZARD_SHELL_OBJDIR ] && rm -rf $HAZARD_SHELL_OBJDIR
     fi
     mkdir -p $HAZARD_SHELL_OBJDIR || true
     cd $HAZARD_SHELL_OBJDIR
-    $JS_SRCDIR/configure --enable-optimize --disable-debug --enable-ctypes --enable-nspr-build --without-intl-api --with-ccache
-    make -j4
+    ( export MOZCONFIG=
+      $JS_SRCDIR/configure --enable-optimize --disable-debug --enable-ctypes --enable-nspr-build --without-intl-api --with-ccache
+      make -j4
+    )
 }
 
 function configure_analysis () {
     local analysis_dir
     analysis_dir="$1"
 
     if [[ -z "$HAZ_DEP" ]]; then
         [ -d "$analysis_dir" ] && rm -rf "$analysis_dir"