old_contents: #! /usr/bin/env python
  #
  # Replaces the extension ".la" with ".so" in the library URI in all 
  # ".cca" files in %{buildroot}%{_datadir}/cca.
  #
  # Mark Piper (mark.piper@colorado.edu)
  
  import os
  import sys
  import glob
  from subprocess import check_call
  
  try:
      install_share_dir = sys.argv[1]
      cca_dir = os.path.join(install_share_dir, "cca")
      print("Modifying *.cca files in " + cca_dir)
      for f in glob.glob(os.path.join(cca_dir, "*.cca")):
          check_call(["sed", "--in-place", "s/\.la/.so/", f])
  except:
      print("Error in post-install modification of *.cca files.")
      sys.exit(1)
  
new_contents: #! /usr/bin/env python
  #
  # Replaces the extension ".la" with ".so" in the library URI in all 
  # ".cca" files in %{buildroot}%{_datadir}/cca.
  #
  # Mark Piper (mark.piper@colorado.edu)
  
  import os
  import sys
  import glob
  from subprocess import check_call
  
  try:
      install_share_dir = sys.argv[1]
      cca_dir = os.path.join(install_share_dir, "cca")
      print("Modifying *.cca files in " + cca_dir)
      for f in glob.glob(os.path.join(cca_dir, "*.cca")):
          check_call(["sed", "--in-place", "s/\.la/.so/", f])
  except:
      print("Error in modification of *.cca files.")
      sys.exit(1)
  
subject: Change wording in error message