patch 8.1.2050: popup window test fails in some configurations

Problem:    Popup window test fails in some configurations. (James McCoy)
Solution:   Clear the command line.

src/testdir/dumps/Test_popupwin_scroll_10.dump

@@ -7,4 +7,4 @@
 |7| @31|║+0#0000001#ffd7ff255|n|i|n|e| | +0#0000000#4040ff13|║+0#0000001#ffd7ff255| +0#0000000#ffffff0@33
 |8| @31|╚+0#0000001#ffd7ff255|═@5|╝| +0#0000000#ffffff0@33
 |9| @73
-|:|c|a|l@1| |p|o|p|u|p|_|s|e|t|o|p|t|i|o|n|s|(|w|i|n|i|d|,| |#|{|m|a|x|h|e|i|g|h|t|:| |0|,| |m|i|n|w|i|d|t|h|:| |0|1|,|1| @10|T|o|p| 
+|:| @55|1|,|1| @10|T|o|p| 

src/testdir/test_popupwin.vim

@@ -1764,6 +1764,7 @@ func Test_popup_scrollbar()
 
   " remove the minwidth and maxheight
   call term_sendkeys(buf, ":call popup_setoptions(winid, #{maxheight: 0, minwidth: 0})\<CR>")
+  call term_sendkeys(buf, ":\<CR>")
   call VerifyScreenDump(buf, 'Test_popupwin_scroll_10', {})
 
   " clean up

src/version.c

@@ -757,6 +757,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2050,
 /**/
     2049,
 /**/