Deterministic order for kernels in notebook UI

IPython/html/services/kernelspecs/handlers.py

@@ -7,6 +7,8 b' from tornado import web'
 
 from ...base.handlers import IPythonHandler, json_errors
 
+from IPython.kernel.kernelspec import _pythonfirst
+
 
 class MainKernelSpecHandler(IPythonHandler):
     SUPPORTED_METHODS = ('GET',)
@@ -16,7 +18,7 b' class MainKernelSpecHandler(IPythonHandler):'
     def get(self):
         ksm = self.kernel_spec_manager
         results = []
-        for kernel_name in ksm.find_kernel_specs():
+        for kernel_name in sorted(ksm.find_kernel_specs(), key=_pythonfirst):
             d = ksm.get_kernel_spec(kernel_name).to_dict()
             d['name'] = kernel_name
             results.append(d)

IPython/kernel/kernelspec.py

@@ -23,6 +23,15 b' else:'
     
 NATIVE_KERNEL_NAME = 'python3' if PY3 else 'python2'
 
+def _pythonfirst(s):
+    "Sort key function that will put strings starting with 'python' first."
+    if s == NATIVE_KERNEL_NAME:
+        return '  ' + s  # Two spaces to sort this first of all
+    elif s.startswith('python'):
+        # Space is not valid in kernel names, so this should sort first
+        return ' ' + s
+    return s
+
 class KernelSpec(HasTraits):
     argv = List()
     display_name = Unicode()

IPython/kernel/kernelspecapp.py

@@ -11,14 +11,7 b' from IPython.core.application import ('
 )
 from IPython.utils.traitlets import Instance, Dict, Unicode, Bool
 
-from .kernelspec import KernelSpecManager
-
-def _pythonfirst(s):
-    "Sort key function that will put strings starting with 'python' first."
-    if s.startswith('python'):
-        # Space is not valid in kernel names, so this should sort first
-        return ' ' + s
-    return s
+from .kernelspec import KernelSpecManager, _pythonfirst
 
 class ListKernelSpecs(BaseIPythonApplication):
     description = """List installed kernel specifications."""