• I am on the latest Poetry version.
• I have searched the issues of this repo and believe that this is not a duplicate.
• If an exception occurs when executing a command, I executed it again in debug mode (-vvv option).

• OS version and name: Windows 10
• Poetry version: 0.12.16
• Link of a Gist with the contents of your pyproject.toml file: N/A

Issue

Found this while fixing handling of pre-release (#1150)

PEP 440 says

• ~=V.N maps to >= V.N, == V.*

Examples

~= 2.2
>= 2.2, == 2.*

~= 1.4.5
>= 1.4.5, == 1.4.*

~= 2.2.0
>= 2.2.0, == 2.2.*

~= 1.4.5.0
>= 1.4.5.0, == 1.4.5.*

but looking at the tests ~=3.5.3 maps to >=3.5.0, < 3.6 when it should map to >=3.5.3, <3.6. The trailing 3 should be setting the floor for the version