Program: 34027
Project: 34027
Buggy source:
public void attemptLogin(){
  if (loginTask != null) {
    return;
  }
  usernameEdit.setError(null);
  passwordEdit.setError(null);
  username=usernameEdit.getText().toString();
  password=passwordEdit.getText().toString();
  boolean cancel=false;
  View focusView=null;
  if (TextUtils.isEmpty(username)) {
    CustomToast.showInCenter(getApplicationContext(),R.string.error_username_required);
    focusView=usernameEdit;
    cancel=true;
  }
 else   if (!username.contains("String_Node_Str") && !username.matches(Constants.REGULAR_EXPRESSION_USERNAME)) {
    CustomToast.showInCenter(getApplicationContext(),R.string.error_invalid_username);
    focusView=usernameEdit;
    cancel=true;
  }
 else   if (TextUtils.isEmpty(password)) {
    CustomToast.showInCenter(getApplicationContext(),R.string.error_password_required);
    focusView=passwordEdit;
    cancel=true;
  }
 else   if (password.contains("String_Node_Str")) {
    CustomToast.showInCenter(getApplicationContext(),R.string.error_invalid_password);
    focusView=passwordEdit;
    cancel=true;
  }
  if (cancel) {
    focusView.requestFocus();
  }
 else {
    customProgressDialog.show(getString(R.string.login_progress_signing_in));
    InputMethodManager inputMethodManager=(InputMethodManager)getSystemService(Context.INPUT_METHOD_SERVICE);
    if (getCurrentFocus() != null) {
      inputMethodManager.hideSoftInputFromWindow(getCurrentFocus().getWindowToken(),0);
    }
    loginTask=new LoginTask();
    loginTask.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
  }
}

Fixed version (ground truth):
public void attemptLogin(){
  if (loginTask != null) {
    return;
  }
  usernameEdit.setError(null);
  passwordEdit.setError(null);
  username=usernameEdit.getText().toString().replace("String_Node_Str","String_Node_Str");
  password=passwordEdit.getText().toString();
  boolean cancel=false;
  View focusView=null;
  if (TextUtils.isEmpty(username)) {
    CustomToast.showInCenter(getApplicationContext(),R.string.error_username_required);
    focusView=usernameEdit;
    cancel=true;
  }
 else   if ((!username.contains("String_Node_Str") && !username.matches(Constants.REGULAR_EXPRESSION_USERNAME))) {
    CustomToast.showInCenter(getApplicationContext(),R.string.error_invalid_username);
    focusView=usernameEdit;
    cancel=true;
  }
 else   if (TextUtils.isEmpty(password)) {
    CustomToast.showInCenter(getApplicationContext(),R.string.error_password_required);
    focusView=passwordEdit;
    cancel=true;
  }
 else   if (password.contains("String_Node_Str")) {
    CustomToast.showInCenter(getApplicationContext(),R.string.error_invalid_password);
    focusView=passwordEdit;
    cancel=true;
  }
  if (cancel) {
    focusView.requestFocus();
  }
 else {
    customProgressDialog.show(getString(R.string.login_progress_signing_in));
    InputMethodManager inputMethodManager=(InputMethodManager)getSystemService(Context.INPUT_METHOD_SERVICE);
    if (getCurrentFocus() != null) {
      inputMethodManager.hideSoftInputFromWindow(getCurrentFocus().getWindowToken(),0);
    }
    loginTask=new LoginTask();
    loginTask.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
  }
}