typesVersions redirect is off-by-one for <= and >

[sandersn]

package.json with the following entry:

  "typesVersions": {
    "<=3.9.0-0": {
      "*": [
        "ts3.9/*"
      ]
    }
  },

Expected behavior:

TS 3.9 (and 3.8, 3.7, ...) should use ts3.9/index.d.ts; TS 4.0 should use index.d.ts

Actual behavior:

TS 3.9 (and 4.0, 4.1) use index.d.ts; TS 3.8, 3.7, ... use ts3.9/index.d.ts.

I wrote a unit test and the same off-by-one error exists for >.

Note: doesn't repro without the trailing '-0', eg <=3.9.0. I'm not sure what this means or why Definitely Typed's package.json uses it.

[sandersn]

@rbuckton can you take a look at this on the off-chance that the trailing -0 means this isn't actually bug?

[sandersn]

Looking at comparePreleaseIdentifiers in semver.ts, this appears to be the intended effect of -0 -- it makes it compare as "prelease", which means that "3.9.0-0" is slightly before "3.9.0". I'm still not sure why DT's package.json uses it -- marking as prerelease seems wrong.