Improve cargo-sweep.sh

[pzmarzly]

See conversation in #212. cargo-sweep will no longer print "error" when cargo-sweep is already installed. Also, updating it should now work.

[realcr]

@pzmarzly : Thanks, I will merge this. I noticed some strange error in one of the integration tests in macOS, I try to restart it. I will check it later and fix if necessary in another PR.

[pzmarzly]

I also experienced the same issue in #215 after Apply cargo fmt commit, restarting the macOS job helped.

[realcr]

I also experienced the same issue in #215 after Apply cargo fmt commit, restarting the macOS job helped.

I added some code to document what happens in the bad integration test (On MacOS). Next time it happens could you include the error? I'm very interested to see what happens there. My guess is some kind of networking problem.

[realcr]

@pzmarzly : I think that I fixed the macOS bug, but I accidentally pushed the fix directly into master. Sorry about that \:

[pzmarzly]

Ready for merging

[realcr]

@pzmarzly : Thanks! Could you check my question above about duplicate if clause in the bash script? Is there a way we can make it more compact?
EDIT: Only now I realized I didn't click on the "request changes". Maybe my question wasn't visible until now (: Sorry!

[realcr]

@pzmarzly : Thanks!