process_robot_output_files: Default gzip arg to env var GZIP

Also, misc. style improvements

Change-Id: I4e9d757a71dd78b122e03a091e58b32c32375702
Signed-off-by: Michael Walsh <micwalsh@us.ibm.com>
diff --git a/lib/gen_call_robot.py b/lib/gen_call_robot.py
index 991ea4c..e336229 100755
--- a/lib/gen_call_robot.py
+++ b/lib/gen_call_robot.py
@@ -32,6 +32,10 @@
 
     This function would typically be called prior to calling
     create_robot_cmd_string.
+
+    Description of argument(s):
+    extra_prefix                    An extra prefix to be appended to the
+                                    default prefix for output file names.
     """
 
     gp.dprint_executing()
@@ -293,7 +297,7 @@
 
 def process_robot_output_files(robot_cmd_buf=None,
                                robot_rc=None,
-                               gzip=1):
+                               gzip=None):
     r"""
     Process robot output files which can involve several operations:
     - If the files are in a temporary location, using SAVE_STATUS_POLICY to
@@ -311,6 +315,7 @@
 
     robot_cmd_buf = gm.dft(robot_cmd_buf, gcr_last_robot_cmd_buf)
     robot_rc = gm.dft(robot_rc, gcr_last_robot_rc)
+    gzip = gm.dft(gzip, int(os.environ.get("GZIP_ROBOT", "1")))
 
     if robot_cmd_buf == "":
         # This can legitimately occur if this function is called from an