Fix breakage due to rust-lang/rust#61856

[ghost]

changelog: none

[ghost]

It looks like rust-lang/rust#61856 broke Map::is_argument(..). Part of this fix should be reverted when that gets fixed. Also, I expected the dogfood test to warn for single_match_else in the is_argument function. Maybe it's a false negative or we're not checking for pedantic lints.

[flip1995]

We check for pedantic lints in dogfood, and this should trigger the lint, weird...

rust-clippy/tests/dogfood.rs

Line 21 in dc69a5c

.args(&["-D", "clippy::pedantic"])

@bors r+ p=1

[bors]

📌 Commit 2f5c1d0 has been approved by flip1995

[bors]

⌛ Testing commit 2f5c1d0 with merge b004461...

[bors]

💔 Test failed - checks-travis

[flip1995]

@bors retry

[bors]

⌛ Testing commit 2f5c1d0 with merge c9c547e...

[bors]

💔 Test failed - checks-travis

[flip1995]

@bors retry

[bors]

⌛ Testing commit 2f5c1d0 with merge e7d153a...

[bors]

☀️ Test successful - checks-travis, status-appveyor
Approved by: flip1995
Pushing e7d153a to master...