bug: conflicting core.bare setting causes segfault during bare clone

["Vusich, Joseph" <jvusich@amazon.com>]

Thank you for filling out a Git bug report!
Please answer the following questions to help us understand your issue.

What did you do before the bug happened? (Steps to reproduce your issue)

$ env | grep GIT

$ git config --list
user.email=jvusich@amazon.com
user.name=Joseph Vusich
core.bare=false

$ git clone --bare https://github.com/josephvusich/fixture
Cloning into bare repository 'fixture.git'...
zsh: segmentation fault  /opt/local/bin/git clone --bare https://github.com/josephvusich/fixture

What did you expect to happen? (Expected behavior)

"git clone --bare" should clone a bare repository, regardless of the core.bare setting in the global config

What happened instead? (Actual behavior)

"git clone --bare" causes a segfault if the global gitconfig has core.bare=false

Anything else you want to add:

* Non-bare clones still work when core.bare=false
* Bare clones only work when core.bare=true, or if core.bare is absent from gitconfig
* Started failing with Git 2.30.0, also fails on 2.30.1, but succeeds on 2.29.2
* Issue reproduced on multiple machines, running Ubuntu, Mac OS, and Alpine Linux
* Running with all TRACEs enabled shows only one additional line prior to "Cloning"
    15:38:08.567292 git.c:444  trace: built-in: git clone --bare https://github.com/josephvusich/fixture
* The fixture.git directory is created prior to the segfault, the fixture.git/config file content is below:
  [core]
    repositoryformatversion = 0
    filemode = true
    bare = false
    logallrefupdates = true

Please review the rest of the bug report below.
You can delete any lines you don't wish to share.


[System Info]
git version:
git version 2.30.1
cpu: x86_64
no commit associated with this build
sizeof-long: 8
sizeof-size_t: 8
shell-path: /bin/sh
uname: Darwin 19.6.0 Darwin Kernel Version 19.6.0: Tue Jan 12 22:13:05 PST 2021; root:xnu-6153.141.16~1/RELEASE_X86_64 x86_64
compiler info: clang: 12.0.0 (clang-1200.0.32.2)
libc info: no libc information available
$SHELL (typically, interactive shell): /bin/zsh


[Enabled Hooks]
not run from a git repository - no hooks to show