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, 2 insertions, 1 deletions

diff --git a/cloudinit/sources/DataSourceConfigDrive.py b/cloudinit/sources/DataSourceConfigDrive.py
index ae31934b..62756cf7 100644
--- a/cloudinit/sources/DataSourceConfigDrive.py
+++ b/cloudinit/sources/DataSourceConfigDrive.py
@@ -10,6 +10,7 @@ import os
 
 from cloudinit import log as logging
 from cloudinit import sources
+from cloudinit import subp
 from cloudinit import util
 
 from cloudinit.net import eni
@@ -245,7 +246,7 @@ def find_candidate_devs(probe_optical=True, dslist=None):
         for device in OPTICAL_DEVICES:
             try:
                 util.find_devs_with(path=device)
-            except util.ProcessExecutionError:
+            except subp.ProcessExecutionError:
                 pass
 
     by_fstype = []