Backport robust parsing to 0.2.x

[pali6]

Unfortunately there are still quite a few crates that depend on 0.2.x version of rustc_version. Internally we hit issues due to what has already been reported in #11 and fixed in #36 because of such crates. Would it be possible to release a 0.2.4 version of rustc_version that backports #36?

I attempted this backporting in https://github.com/pali6/rustc-version-rs/tree/0.2.x-backport, getting rid of the bits of #36 that are not relevant for 0.2.3.

[djc]

What crates have you run into that are still on 0.2.x? Have you tried to get them to update?

[pali6]

That is also in the works (e.g. cortex-m hopefully removing the dependency on the deprecated bare-metal, an older version of which depends on rustc_version 0.2.x, or Alexhuszagh/float16#15). But it would be nice if we could just tell internal teams to run cargo update to fix this particular issue no matter what the dependency tree is, especially as more of these cases might get discovered over time.

[djc]

Okay, I will review a PR. It should contain one commit per commit you're porting from the other branch, and one commit with a version bump.

[pali6]

Sounds good. There is currently no 0.2.x branch on this repo. Could you create one from the v0.2.3 tag so I have a branch to PR against?