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) {
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<tr><td><span title='2017-04-03 14:51:49 +0200'>2017-04-03</span></td><td><a href='/guix/commit/gnu/packages/ed.scm?id=1f044d7a910bfe6b3aa264e876418f4a96e0aece'>gnu: ed: Update to 1.14.2.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/ed.scm (ed): Update to 1.14.2.
</span></span></td><td>Marius Bakke</td></tr>
<tr><td><span title='2017-01-12 23:28:59 +0100'>2017-01-12</span></td><td><a href='/guix/commit/gnu/packages/ed.scm?id=e9384e3b746eb96beea6d3a9dce5f504825e8baa'>gnu: ed: Update to 1.14.1.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/ed.scm (ed): Update to 1.14.1.
[arguments]: Make sure 'patch-test-suite' phase ends with #t.
[home-page]: Use HTTPS.
</span></span></td><td>Marius Bakke</td></tr>
<tr><td><span title='2016-02-15 10:17:46 +0200'>2016-02-15</span></td><td><a href='/guix/commit/gnu/packages/ed.scm?id=ff0c847687ce796d61c94ca07ffa6d646339d095'>gnu: ed: Use 'modify-phases'.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/ed.scm (ed)[arguments]: Use 'modify-phases'.
</span></span></td><td>Efraim Flashner</td></tr>
<tr><td><span title='2016-02-15 10:17:45 +0200'>2016-02-15</span></td><td><a href='/guix/commit/gnu/packages/ed.scm?id=5cd2c1e8c1dc3b0a18c2c6d4f2432b81e3a55f75'>gnu: ed: Update to 1.13.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/ed.scm (ed): Update to 1.13.
</span></span></td><td>Efraim Flashner</td></tr>
<tr><td><span title='2015-07-10 23:47:08 -0400'>2015-07-10</span></td><td><a href='/guix/commit/gnu/packages/ed.scm?id=302af59fc14c6dc3686a24d4e11429f719c0c7d1'>gnu: ed: Update to 1.12.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/ed.scm (ed): Update to 1.12.
</span></span></td><td>Mark H Weaver</td></tr>
<tr><td><span title='2015-04-04 03:46:55 -0400'>2015-04-04</span></td><td><a href='/guix/commit/gnu/packages/ed.scm?id=353fda815e8b7863408857048aff224bbd0716d5'>gnu: ed: Update to 1.11.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/ed.scm (ed): Update to 1.11.
</span></span></td><td>Mark H Weaver</td></tr>