Pre-upgrade Check Version Specification Debate

Summary of what's been discussed.

The original requested way that it should work is illustrated in this example:

Original

<compatibility>
  <version>1.5</version>
  <version>2.5</version>
  <version>3.0.1</version>
  <version>4</version>
<compatibility>

Is interpretted as: Joomla 1.5: compatible

Joomla 1.6: not compatible

Joomla 1.7: not compatible

Joomla 2.5: compatible

Joomla 3.0: compatible for 3.0.1 and up in the 3.0 version

Joomla 3.1: not compatible

Joomla 3.2: not compatible

Joomla 3.5: not compatible

Joomla 4:0: compatible

Joomla 4.1: compatible

Joomla 4.2: compatible

Joomla 4.5: compatible ---End of Original---

It was accidentally coded as: ---Accidentally coded as--- <compatibility>

 <version>1.5</version>
 <version>2.5</version>
 <version>3.0.1</version>
 <version>4</version>

<compatibility>

Is interpretted as: Joomla 1.5: compatible Joomla 1.6: not compatible Joomla 1.7: not compatible Joomla 2.5: compatible Joomla 3.0: compatible only for 3.0.1 Joomla 3.1: not compatible Joomla 3.2: not compatible Joomla 3.5: not compatible Joomla 4:0: compatible Joomla 4.1: compatible Joomla 4.2: compatible Joomla 4.5: compatible ---end of Accidentally coded as---

The above was changed to the original specifications, but some people continued to argue whether "3.0.1" should mean "compatible for 3.0.1 through 3.0.x" or "only for 3.0.1".

Others thought, we shouldn't use either of the above, but should use: http://getcomposer.org/doc/01-basic-usage.md#package-versions

99%-100% of the code is written for the original implementation. The getcomposer approach is not written.