Auto merge of #1262 - gnzlbg:rustfmt_fail, r=gnzlbg
Auto merge of #1262 - gnzlbg:rustfmt_fail, r=gnzlbg

Allow installing rustfmt component to fail

rust-lang/libc,rust-lang-nursery/libc,rust-lang/libc,rust-lang/libc,rust-lang-nursery/libc,rust-lang-nursery/libc