How to update posh-git
All it does is look if the script is being sourced in your profile:
$profileLine = ". '$installDir\profile.example.ps1'"if(Select-String -Path $PROFILE -Pattern $profileLine -Quiet -SimpleMatch) { Write-Host "It seems posh-git is already installed..." return}Since it seems to have the installDir as the folder from which you run the install script, merely upgrading the folder with the newer version of posh-git should give have updated the files already.
If you are not comfortable with that, just remove the line that sources the profile.example.ps1 in your profile and run the install again :)
I had installed via PsGet, so I renamed the folder
C:\Users\[myName]\Documents\WindowsPowerShell\Modules\posh-git
and re-ran
Install-Module posh-git
It downloaded the latest but told me it was already installed, probably because I hadn't removed the lines from Microsoft.PowerShell_profile.ps1. That was all I needed, though.