diff --git a/notebook/_sysinfo.py b/notebook/_sysinfo.py
index ea237bbd2a..4e6a366266 100644
--- a/notebook/_sysinfo.py
+++ b/notebook/_sysinfo.py
@@ -46,11 +46,15 @@ def pkg_commit_hash(pkg_path):
     while cur_path != par_path:
         cur_path = par_path
         if p.exists(p.join(cur_path, '.git')):
-            proc = subprocess.Popen('git rev-parse --short HEAD',
-                                stdout=subprocess.PIPE,
-                                stderr=subprocess.PIPE,
-                                cwd=pkg_path, shell=True)
-            repo_commit, _ = proc.communicate()
+            try:
+                proc = subprocess.Popen(['git', 'rev-parse', '--short', 'HEAD'],
+                                    stdout=subprocess.PIPE,
+                                    stderr=subprocess.PIPE,
+                                    cwd=pkg_path)
+                repo_commit, _ = proc.communicate()
+            except OSError:
+                repo_commit = None
+
             if repo_commit:
                 return 'repository', repo_commit.strip().decode('ascii')
             else:
diff --git a/notebook/base/handlers.py b/notebook/base/handlers.py
index 2c48d5cc14..cf3e183f09 100755
--- a/notebook/base/handlers.py
+++ b/notebook/base/handlers.py
@@ -39,7 +39,12 @@
 #-----------------------------------------------------------------------------
 non_alphanum = re.compile(r'[^A-Za-z0-9]')
 
-sys_info = json.dumps(get_sys_info())
+_sys_info_cache = None
+def json_sys_info():
+    global _sys_info_cache
+    if _sys_info_cache is None:
+        _sys_info_cache = json.dumps(get_sys_info())
+    return _sys_info_cache
 
 def log():
     if Application.initialized():
@@ -357,7 +362,7 @@ def template_namespace(self):
             login_available=self.login_available,
             token_available=bool(self.token or self.one_time_token),
             static_url=self.static_url,
-            sys_info=sys_info,
+            sys_info=json_sys_info(),
             contents_js_source=self.contents_js_source,
             version_hash=self.version_hash,
             ignore_minified_js=self.ignore_minified_js,