From upstream PR: https://github.com/urfave/cli/pull/1299

From: William Wilson <william.wilson@canonical.com>
Date: Tue, 31 Aug 2021 14:19:17 -0500
Subject: Make test case compatible with Go 1.17

As of Go 1.17, the go flag package will panic if given a syntactically invalid
flag. This causes TestApp_RunAsSubCommandIncorrectUsage to panic and therefore
fail. See https://golang.org/doc/go1.17#flag for more information.

---
diff --git a/app_test.go b/app_test.go
index 7c38f6048..76e211d68 100644
--- a/app_test.go
+++ b/app_test.go
@@ -476,18 +476,18 @@ func TestApp_RunAsSubCommandIncorrectUsage(t *testing.T) {
 	a := App{
 		Name: "cmd",
 		Flags: []Flag{
-			&StringFlag{Name: "--foo"},
+			&StringFlag{Name: "foo"},
 		},
 		Writer: bytes.NewBufferString(""),
 	}
 
 	set := flag.NewFlagSet("", flag.ContinueOnError)
-	_ = set.Parse([]string{"", "---foo"})
+	_ = set.Parse([]string{"", "-bar"})
 	c := &Context{flagSet: set}
 
 	err := a.RunAsSubcommand(c)
 
-	expect(t, err, errors.New("bad flag syntax: ---foo"))
+	expect(t, err.Error(), "flag provided but not defined: -bar")
 }
 
 func TestApp_CommandWithFlagBeforeTerminator(t *testing.T) {
guix/tree/THANKS?id=0759cde4fe97b7dc467ea7ce7b121a9a0e44a78a'>tree</a><a href='/guix/commit/THANKS?id=0759cde4fe97b7dc467ea7ce7b121a9a0e44a78a'>commit</a><a href='/guix/diff/THANKS?id=0759cde4fe97b7dc467ea7ce7b121a9a0e44a78a'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/THANKS'>
<input type='hidden' name='id' value='0759cde4fe97b7dc467ea7ce7b121a9a0e44a78a'/><select name='qt'>
<option value='grep'>log msg</option>
<option value='author'>author</option>
<option value='committer'>committer</option>
<option value='range'>range</option>
</select>
<input class='txt' type='search' size='10' name='q' value=''/>
<input type='submit' value='search'/>
</form>
</td></tr></table>
<div class='path'>path: <a href='/guix/log/?id=0759cde4fe97b7dc467ea7ce7b121a9a0e44a78a'>root</a>/<a href='/guix/log/THANKS?id=0759cde4fe97b7dc467ea7ce7b121a9a0e44a78a'>THANKS</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/THANKS?id=0759cde4fe97b7dc467ea7ce7b121a9a0e44a78a&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>