Move subp into its own module. (#416)

This was painful, but it finishes a TODO from cloudinit/subp.py.

It moves the following from util to subp:
  ProcessExecutionError
  subp
  which
  target_path

I moved subp_blob_in_tempfile into cc_chef, which is its only caller.
That saved us from having to deal with it using write_file
and temp_utils from subp (which does not import any cloudinit things now).

It is arguable that 'target_path' could be moved to a 'path_utils' or
something, but in order to use it from subp and also from utils,
we had to get it out of utils.

1 files changed, 3 insertions, 2 deletions

diff --git a/cloudinit/handlers/boot_hook.py b/cloudinit/handlers/boot_hook.py
index dca50a49..c6205097 100644
--- a/cloudinit/handlers/boot_hook.py
+++ b/cloudinit/handlers/boot_hook.py
@@ -12,6 +12,7 @@ import os
 
 from cloudinit import handlers
 from cloudinit import log as logging
+from cloudinit import subp
 from cloudinit import util
 
 from cloudinit.settings import (PER_ALWAYS)
@@ -48,8 +49,8 @@ class BootHookPartHandler(handlers.Handler):
             env = os.environ.copy()
             if self.instance_id is not None:
                 env['INSTANCE_ID'] = str(self.instance_id)
-            util.subp([filepath], env=env)
-        except util.ProcessExecutionError:
+            subp.subp([filepath], env=env)
+        except subp.ProcessExecutionError:
             util.logexc(LOG, "Boothooks script %s execution error", filepath)
         except Exception:
             util.logexc(LOG, "Boothooks unknown error when running %s",