patch 8.0.0446: the ";" command does not work after some characters

Problem:    The ";" command does not work after characters with a lower byte
            that is NUL.
Solution:   Properly check for not having a previous character. (Hirohito
            Higashi)

src/Makefile

@@ -2099,6 +2099,7 @@ test_arglist \
 	test_cdo \
 	test_channel \
 	test_charsearch \
+	test_charsearch_utf8 \
 	test_changedtick \
 	test_cindent \
 	test_cmdline \

src/search.c

@@ -1643,7 +1643,11 @@ searchc(cmdarg_T *cap, int t_cmd)
     }
     else		/* repeat previous search */
     {
-	if (*lastc == NUL)
+	if (*lastc == NUL
+#ifdef FEAT_MBYTE
+		&& lastc_bytelen == 1
+#endif
+		)
 	    return FAIL;
 	if (dir)	/* repeat in opposite direction */
 	    dir = -lastcdir;

src/testdir/test_alot_utf8.vim

@@ -6,6 +6,7 @@
 " files, so that they can be run by themselves.
 
 set belloff=all
+source test_charsearch_utf8.vim
 source test_expr_utf8.vim
 source test_matchadd_conceal_utf8.vim
 source test_regexp_utf8.vim

src/testdir/test_charsearch_utf8.vim

@@ -0,0 +1,44 @@
+" Tests for related f{char} and t{char} using utf-8.
+if !has('multi_byte')
+  finish
+endif
+
+" Test for t,f,F,T movement commands
+function! Test_search_cmds()
+  new!
+  call setline(1, "・最初から最後まで最強のVimは最高")
+  1
+  normal! f最
+  call assert_equal([0, 1, 4, 0], getpos('.'))
+  normal! ;
+  call assert_equal([0, 1, 16, 0], getpos('.'))
+  normal! 2;
+  call assert_equal([0, 1, 43, 0], getpos('.'))
+  normal! ,
+  call assert_equal([0, 1, 28, 0], getpos('.'))
+  bw!
+endfunction
+
+" vim: shiftwidth=2 sts=2 expandtab
+" Tests for related f{char} and t{char} using utf-8.
+if !has('multi_byte')
+  finish
+endif
+
+" Test for t,f,F,T movement commands
+function! Test_search_cmds()
+  new!
+  call setline(1, "・最初から最後まで最強のVimは最高")
+  1
+  normal! f最
+  call assert_equal([0, 1, 4, 0], getpos('.'))
+  normal! ;
+  call assert_equal([0, 1, 16, 0], getpos('.'))
+  normal! 2;
+  call assert_equal([0, 1, 43, 0], getpos('.'))
+  normal! ,
+  call assert_equal([0, 1, 28, 0], getpos('.'))
+  bw!
+endfunction
+
+" vim: shiftwidth=2 sts=2 expandtab

src/version.c

@@ -764,6 +764,10 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    446,
+/**/
+    446,
 /**/
     445,
 /**/