patch 8.2.0215: wrong file name shortening

Problem:    Wrong file name shortening. (Ingo Karkat)
Solution:   Better check for path separator. (Yasuhiro Matsumoto,
            closes #5583, closes #5584)

src/filepath.c

@@ -448,17 +448,21 @@ repeat:
 		if (fnamencmp(p, dirname, namelen) == 0)
 		{
 		    p += namelen;
+		    if (vim_ispathsep(*p))
+		    {
 			while (*p && vim_ispathsep(*p))
 			    ++p;
 			*fnamep = p;
 			if (pbuf != NULL)
 			{
-			vim_free(*bufp);   // free any allocated file name
+			    // free any allocated file name
+			    vim_free(*bufp);
 			    *bufp = pbuf;
 			    pbuf = NULL;
 			}
 		    }
 		}
+	    }
 	    else
 	    {
 		home_replace(NULL, p, dirname, MAXPATHL, TRUE);

src/testdir/test_fnamemodify.vim

@@ -36,6 +36,8 @@ func Test_fnamemodify()
   call chdir($HOME . '/XXXXXXXX/a/')
   call assert_equal('foo', fnamemodify($HOME . '/XXXXXXXX/a/foo', ':p:~:.'))
   call assert_equal('~/XXXXXXXX/b/foo', fnamemodify($HOME . '/XXXXXXXX/b/foo', ':p:~:.'))
+  call mkdir($HOME . '/XXXXXXXX/a.ext', 'p')
+  call assert_equal('~/XXXXXXXX/a.ext/foo', fnamemodify($HOME . '/XXXXXXXX/a.ext/foo', ':p:~:.'))
   call chdir(cwd)
   call delete($HOME . '/XXXXXXXX', 'rf')
 

src/version.c

@@ -742,6 +742,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    215,
 /**/
     214,
 /**/