Clean up use of subprocess

slapos/recipe/cmmi/README.txt

@@ -1048,7 +1048,7 @@ process as the recipe tried.
     Installing package.
     package: Checking whether package is installed at shared path: .../slapos.recipe.cmmi/slapos/recipe/cmmi/shared/package/...
     package: [ENV] FOO = bar
-    package: Command failed with exit code 127: ./configure --prefix=".../slapos.recipe.cmmi/slapos/recipe/cmmi/shared/package/..."
+    package: Command './configure --prefix=".../slapos.recipe.cmmi/slapos/recipe/cmmi/shared/package/..."' returned non-zero exit status 127
     package: Compilation error. The package is left as is at .../slapos.recipe.cmmi/slapos/recipe/cmmi/shared/package/...__compile__ where you can inspect what went wrong.
     A shell script slapos.recipe.build.env.sh has been generated. You can source it in your shell to reproduce build environment.
     /bin/sh: 1: ./configure: not found

slapos/recipe/cmmi/__init__.py

@@ -213,17 +213,10 @@ class Recipe(object):
         log = logging.getLogger(self.name)
         args = ['find', self.buildout_prefix, '-cnewer', ref_file, '!', '-type', 'd']
         try:
-            p = subprocess.Popen(args, stdout=subprocess.PIPE, universal_newlines=True)
-            files, _ = p.communicate()
-            retcode = p.returncode
-            if retcode < 0:
-                log.error('Command received signal %s: %s' % (-retcode, args))
-                raise zc.buildout.UserError('System error')
-            elif retcode > 0:
-                log.error('Command failed with exit code %s: %s' % (retcode, args))
-                raise zc.buildout.UserError('System error')
-        except OSError as e:
-            log.error('Command failed: %s: %s' % (e, args))
+            files = subprocess.check_output(args,
+                universal_newlines=True, close_fds=True)
+        except Exception as e:
+            log.error(e)
             raise zc.buildout.UserError('System error')
         return files.splitlines()
 
@@ -262,16 +255,10 @@ class Recipe(object):
         """Run the given ``cmd`` in a child process."""
         log = logging.getLogger(self.name)
         try:
-            retcode = subprocess.call(cmd, shell=True, env=self.augmented_environment(), close_fds=True)
-
-            if retcode < 0:
-                log.error('Command received signal %s: %s' % (-retcode, cmd))
-                raise zc.buildout.UserError('System error')
-            elif retcode > 0:
-                log.error('Command failed with exit code %s: %s' % (retcode, cmd))
-                raise zc.buildout.UserError('System error')
-        except OSError as e:
-            log.error('Command failed: %s: %s' % (e, cmd))
+            subprocess.check_call(cmd, shell=True,
+                env=self.augmented_environment(), close_fds=True)
+        except Exception as e:
+            log.error(e)
             raise zc.buildout.UserError('System error')
 
     def install(self):