Running cargo update without a Cargo.lock ignores arguments

[glandium]

Problem
Say you want to test a crate against a specific version of one of its dependencies. One way to do that is to run cargo update -p $dep --precise $version. The problem is that when you do that without a pre-existing Cargo.lock (like, running that as the first command in a travis script), all the arguments are ignored, and you get the same Cargo.lock as you would plain cargo update, so without $dep at the wanted $version.

Notes

Output of cargo version:

cargo 1.34.0 (6789d8a0a 2019-04-01)

[fluffysquirrels]

I'm taking a look at this.

[ehuss]

This was fixed by #6904.