message: Update variables.py
  Changed ValueError messages to format the passed parameter in the error message.
diff: @@ -416,7 +416,7 @@ def get_unique_variable(var_op_name):
  for candidate in candidates:
  if candidate.op.name == var_op_name:
  return candidate
  - raise ValueError('Variable %s does not uniquely identify a variable',
  + raise ValueError('Variable %s does not uniquely identify a variable' %
  var_op_name)
  @@ -444,7 +444,7 @@ def assign_from_values(var_names_to_values):
  var_value = var_names_to_values[var_name]
  var = ops.get_collection(ops.GraphKeys.GLOBAL_VARIABLES, var_name)
  if not var:
  - raise ValueError('Variable %s wasnt found', var_name)
  + raise ValueError('Variable %s wasn\'t found' % var_name)
  elif len(var) > 1:
  # tf.get_collection is just a filter on the prefix: find the exact match:
  found = False
  @@ -455,7 +455,7 @@ def assign_from_values(var_names_to_values):
  break
  if not found:
  - raise ValueError('Variable %s doesnt uniquely identify a variable',
  + raise ValueError('Variable %s doesn\'t uniquely identify a variable' %
  var_name)
  else:
  var = var[0]
  