Remove code duplication and improve style.

scm.py

Index: scm.py
diff --git a/scm.py b/scm.py
index 1f242191999604c48c6563637db38eff38cfc3d3..924f1264166032b21fda748b7de066ce9e3a4c2f 100644
--- a/scm.py
+++ b/scm.py
@@ -215,7 +215,7 @@ class GIT(object):
       # pipe at a time.
       # The -100 is an arbitrary limit so we don't search forever.
       cmd = ['git', 'log', '-100', '--pretty=medium']
-      proc = subprocess.Popen(cmd, stdout=subprocess.PIPE, cwd=cwd)
+      proc = gclient_utils.Popen(cmd, stdout=subprocess.PIPE, cwd=cwd)
       for line in proc.stdout:
         match = git_svn_re.match(line)
         if match:
@@ -371,19 +371,11 @@ class SVN(object):
     """
     c = [SVN.COMMAND]
     c.extend(args)
-
-    # *Sigh*:  Windows needs shell=True, or else it won't search %PATH% for
-    # the svn.exe executable, but shell=True makes subprocess on Linux fail
-    # when it's called with a list because it only tries to execute the
-    # first string ("svn").
     stderr = None
     if not print_error:
       stderr = subprocess.PIPE
-    return subprocess.Popen(c,
-                            cwd=in_directory,
-                            shell=(sys.platform == 'win32'),
-                            stdout=subprocess.PIPE,
-                            stderr=stderr).communicate()[0]
+    return gclient_utils.Popen(c, cwd=in_directory, stdout=subprocess.PIPE,
+        stderr=stderr).communicate()[0]
 
   @staticmethod
   def RunAndGetFileList(verbose, args, in_directory, file_list):