Commiting asks for user data although they are set via includeif

What steps will reproduce the problem?

1. Edit your .gitconfig using conditional includes via includeif (https://git-scm.com/docs/git-config#_includes) like this

   [includeIf "gitdir:**/gitlab/**"]
     	path = .gitconfig-gitlab
   [includeIf "gitdir:**/CC/**"]
     	path = .gitconfig-codecentric

   Both files contain different user info like this

   [user]
       name = ccHanibal
       email = oliver.daum@codecentric.de

2. Try to commit a repository that is located under the gitlab folder.

What is the expected output? What do you see instead?

I expect to see the commit dialog. Instead I'm asked to set user name and email first.

When I click yes, the settings dialog appears and it already shows the username and email configuration that is included via includeif.
Leaving the dialog with OK presents the first dialog again.

What version of TortoiseGit and Git are you using? On what operating system?

TortoiseGit 2.6.0.0
Git for windows 2.16.2.windows.1
Windows 7

Please provide any additional information below.

In TortoiseGit 2.5.0.0 it worked fine, so seems to be a regression in 2.6.0.0.