patch 8.0.1643: terminal API tests fail

Problem:    Terminal API tests fail.
Solution:   Explicitly set 'title'.

src/testdir/test_terminal.vim

@@ -1029,6 +1029,7 @@ func Test_terminal_api_drop_newwin()
     return
   endif
   call assert_equal(1, winnr('$'))
+  set title
 
   " Use the title termcap entries to output the escape sequence.
   call writefile([
@@ -1045,6 +1046,7 @@ func Test_terminal_api_drop_newwin()
   call StopVimInTerminal(buf)
   call delete('Xscript')
   bwipe Xtextfile
+  set title&
 endfunc
 
 func Test_terminal_api_drop_oldwin()
@@ -1056,6 +1058,7 @@ func Test_terminal_api_drop_oldwin()
   let textfile_winid = win_getid()
   call assert_equal(2, winnr('$'))
   call win_gotoid(firstwinid)
+  set title
 
   " Use the title termcap entries to output the escape sequence.
   call writefile([
@@ -1071,6 +1074,7 @@ func Test_terminal_api_drop_oldwin()
   call StopVimInTerminal(buf)
   call delete('Xscript')
   bwipe Xtextfile
+  set title&
 endfunc
 
 func TryThis(bufnum, arg)
@@ -1082,6 +1086,8 @@ func Test_terminal_api_call()
   if !CanRunVimInTerminal()
     return
   endif
+  set title
+
   " Use the title termcap entries to output the escape sequence.
   call writefile([
 	\ 'exe "set t_ts=\<Esc>]51; t_fs=\x07"',
@@ -1098,4 +1104,5 @@ func Test_terminal_api_call()
   call delete('Xscript')
   unlet g:called_bufnum
   unlet g:called_arg
+  set title&
 endfunc

src/version.c

@@ -766,6 +766,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1643,
 /**/
     1642,
 /**/