patch 8.1.2255: ":term ++shell" does not work on MS-Windows

Problem:    ":term ++shell" does not work on MS-Windows.
Solution:   Add MS-Windows support.
diff --git a/src/terminal.c b/src/terminal.c
index 290d7c7..a3ca993 100644
--- a/src/terminal.c
+++ b/src/terminal.c
@@ -846,21 +846,31 @@
 	    term_start(NULL, argv, &opt, eap->forceit ? TERM_START_FORCEIT : 0);
 	vim_free(tofree1);
 	vim_free(tofree2);
+	goto theend;
 #else
+# ifdef MSWIN
+	long_u	    cmdlen = STRLEN(p_sh) + STRLEN(p_shcf) + STRLEN(cmd) + 10;
+	char_u	    *newcmd;
+
+	newcmd = alloc(cmdlen);
+	if (newcmd == NULL)
+	    goto theend;
+	tofree = newcmd;
+	vim_snprintf((char *)newcmd, cmdlen, "%s %s %s", p_sh, p_shcf, cmd);
+	cmd = newcmd;
+# else
 	emsg(_("E279: Sorry, ++shell is not supported on this system"));
+	goto theend;
+# endif
 #endif
     }
-    else
-    {
-	argvar[0].v_type = VAR_STRING;
-	argvar[0].vval.v_string = cmd;
-	argvar[1].v_type = VAR_UNKNOWN;
-	term_start(argvar, NULL, &opt, eap->forceit ? TERM_START_FORCEIT : 0);
-    }
-
-    vim_free(tofree);
+    argvar[0].v_type = VAR_STRING;
+    argvar[0].vval.v_string = cmd;
+    argvar[1].v_type = VAR_UNKNOWN;
+    term_start(argvar, NULL, &opt, eap->forceit ? TERM_START_FORCEIT : 0);
 
 theend:
+    vim_free(tofree);
     vim_free(opt.jo_eof_chars);
 }
 
diff --git a/src/testdir/test_terminal.vim b/src/testdir/test_terminal.vim
index 1a126b9..ba17959 100644
--- a/src/testdir/test_terminal.vim
+++ b/src/testdir/test_terminal.vim
@@ -2215,15 +2215,25 @@
 endfunc
 
 func Test_terminal_shell_option()
-  CheckUnix
-  " exec is a shell builtin command, should fail without a shell.
-  term exec ls runtest.vim
-  call WaitForAssert({-> assert_match('job failed', term_getline(bufnr(), 1))})
-  bwipe!
+  if has('unix')
+    " exec is a shell builtin command, should fail without a shell.
+    term exec ls runtest.vim
+    call WaitForAssert({-> assert_match('job failed', term_getline(bufnr(), 1))})
+    bwipe!
 
-  term ++shell exec ls runtest.vim
-  call WaitForAssert({-> assert_match('runtest.vim', term_getline(bufnr(), 1))})
-  bwipe!
+    term ++shell exec ls runtest.vim
+    call WaitForAssert({-> assert_match('runtest.vim', term_getline(bufnr(), 1))})
+    bwipe!
+  elseif has('win32')
+    " dir is a shell builtin command, should fail without a shell.
+    term dir /b runtest.vim
+    call WaitForAssert({-> assert_match('job failed', term_getline(bufnr(), 1))})
+    bwipe!
+
+    term ++shell dir /b runtest.vim
+    call WaitForAssert({-> assert_match('runtest.vim', term_getline(bufnr(), 1))})
+    bwipe!
+  endif
 endfunc
 
 func Test_terminal_setapi_and_call()
diff --git a/src/version.c b/src/version.c
index 79f3576..4315a17 100644
--- a/src/version.c
+++ b/src/version.c
@@ -742,6 +742,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2255,
+/**/
     2254,
 /**/
     2253,