Why does Composer say "Conclusion: don't install" when (seemingly) no obstacles are present?

The following composer.json:

{
    "type": "project",
    "minimum-stability": "dev",
    "require": {
        "jasny/bootstrap": ">=3.1.3",
        "2amigos/yii2-file-input-widget": "*"
    }
}

leads to the following output of composer update:

Loading composer repositories with package information
Updating dependencies (including require-dev)
Your requirements could not be resolved to an installable set of packages.                               

  Problem 1
    - 2amigos/yii2-file-input-widget 0.1.2 requires jasny/bootstrap v3.1.0 -> satisfiable by jasny/bootstrap[v3.1.0] but these conflict with your requirements or minimum-stability.
    - 2amigos/yii2-file-input-widget 0.1.1 requires jasny/bootstrap v3.1.0 -> satisfiable by jasny/bootstrap[v3.1.0] but these conflict with your requirements or minimum-stability.
    - 2amigos/yii2-file-input-widget 0.1.0 requires jasny/bootstrap v3.1.0 -> satisfiable by jasny/bootstrap[v3.1.0] but these conflict with your requirements or minimum-stability.
    - 2amigos/yii2-file-input-widget 1.0.0 requires jasny/bootstrap ~3.1.0 -> satisfiable by jasny/bootstrap[v3.1.3].
    - 2amigos/yii2-file-input-widget 1.0.1 requires jasny/bootstrap ~3.1.0 -> satisfiable by jasny/bootstrap[v3.1.3].
    - 2amigos/yii2-file-input-widget 1.0.2 requires jasny/bootstrap ~3.1.0 -> satisfiable by jasny/bootstrap[v3.1.3].
    - 2amigos/yii2-file-input-widget dev-master requires jasny/bootstrap ~3.1.0 -> satisfiable by jasny/bootstrap[v3.1.3].
    - 2amigos/yii2-file-input-widget 1.0.x-dev requires jasny/bootstrap ~3.1.0 -> satisfiable by jasny/bootstrap[v3.1.3].
    - Conclusion: don't install jasny/bootstrap v3.1.3
    - Installation request for 2amigos/yii2-file-input-widget * -> satisfiable by 2amigos/yii2-file-input-widget[0.1.0, 0.1.1, 0.1.2, 1.0.0, 1.0.1, 1.0.2, dev-master, 1.0.x-dev].

Why?

Ok, I understand, why versions 0.1.0–0.1.2 of 2amigos/yii2-file-input-widget can't be installed — because they require jasny/bootstrap of exact version 3.1.0, which conflicts with >=3.1.3 requirement in composer.json (and therefore composer clarifies: but these conflict with your requirements or minimum-stability).

But, from common-sense view, composer can install version 1.0.0 or later of 2amigos/yii2-file-input-widget (which requires jasny/bootstrap of version ~3.1.0, which is satisfiable by 3.1.3). Neither I see any obstacles for installing 2amigos/yii2-file-input-widget 1.0.0+ together with jasny/bootstrap 3.1.3, nor composer writes any explicit clarification about it. Still it says: Conclusion: don't install jasny/bootstrap v3.1.3 — why?

Workaround 1

It seems it works with "prefer-stable": true.

Workaround 2

I actually found the other workaround some time ago: I replace "2amigos/yii2-file-input-widget": "*" with "2amigos/yii2-file-input-widget": "1.0.2", do composer update and then replace it back and do composer update again — and it works.

The question is why it works in so strange way: why it works with more restrictions, but fails with less restrictions (with no clarification). E.g. if it works with 1.0.2 (or with prefer-stable) works — then why it doesn't with * (or without prefer-stable)?