patch 8.0.1304: CTRL-G/CTRL-T don't work with incsearch and empty pattern

Problem:    CTRL-G/CTRL-T don't work with incsearch and empty pattern.
Solution:   Use the last search pattern. (Christian Brabandt, closes #2292)
diff --git a/src/testdir/test_search.vim b/src/testdir/test_search.vim
index 2a660c6..d13e654 100644
--- a/src/testdir/test_search.vim
+++ b/src/testdir/test_search.vim
@@ -461,6 +461,15 @@
   " moves to next match of previous search pattern, just like /<cr>
   call feedkeys("/\<c-t>\<cr>", 'tx')
   call assert_equal([0,1,7,0], getpos('.'))
+
+  " using an offset uses the last search pattern
+  call cursor(1, 1)
+  call setline(1, ['1 bbvimb', ' 2 bbvimb'])
+  let @/ = 'b'
+  call feedkeys("//e\<c-g>\<cr>", 'tx')
+  call assert_equal('1 bbvimb', getline('.'))
+  call assert_equal(4, col('.'))
+
   set noincsearch
   call test_override("char_avail", 0)
   bw!