Fix tests after "use new main branch"

Tests worked fine if init.defaultBranch main was used,
but failed due to git branch reasons if master was still used.

Since we can only use init.defaultBranch if git version >= 2.28,
I also went with a template dir HEAD main tweak if lower so tests
now pass regardless of client git default branch and version.

Test: Ran tests with ~/.gitconfig:init.defaultBranch=master
Test: Ran tests with ~/.gitconfig:init.defaultBranch=main
Test: Ran tests for both code branches of git require

Change-Id: I49fa1e4ae45b8aec16a093132ee9fa466cbc11ec
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/290404
Tested-by: Fredrik de Groot <fredrik.de.groot@volvocars.com>
Reviewed-by: Mike Frysinger <vapier@google.com>

0 files changed, 0 insertions, 0 deletions