patch 8.2.2776: :mksession uses current value of 'splitbelow' and 'splitright'

Problem:    :mksession uses current value of 'splitbelow' and 'splitright'
            even though "options" is not in 'sessionoptions'. (Maxim Kim)
Solution:   Save and restore the values, instead of setting to the current
            value. (closes #8119)
diff --git a/src/testdir/test_mksession.vim b/src/testdir/test_mksession.vim
index 8eed111..25c5081 100644
--- a/src/testdir/test_mksession.vim
+++ b/src/testdir/test_mksession.vim
@@ -911,6 +911,24 @@
   set sessionoptions&
 endfunc
 
+" Test for mksession without options restores winminheight
+func Test_mksession_winminheight()
+  set sessionoptions-=options
+  split
+  mksession! Xtest_mks.out
+  let found_restore = 0
+  let lines = readfile('Xtest_mks.out')
+  for line in lines
+    if line =~ '= s:save_winmin\(width\|height\)'
+      let found_restore += 1
+    endif
+  endfor
+  call assert_equal(2, found_restore)
+  call delete('Xtest_mks.out')
+  close
+  set sessionoptions&
+endfunc
+
 " Test for mksession with 'compatible' option
 func Test_mksession_compatible()
   mksession! Xtest_mks1.out