pythonでmysqlclientが入らずエラーが出る(なんとか解決はしたが理由は不明)

mysqlclientが入らない。以下のエラーが出る

```
Installing collected packages: mysqlclient, pytz, urllib3, requests, sb-django-redis-sentinel
  Found existing installation: mysqlclient 1.3.13
    Uninstalling mysqlclient-1.3.13:
      Successfully uninstalled mysqlclient-1.3.13
  Running setup.py install for mysqlclient ... error
    Complete output from command /Users/masato-naka/.pyenv/versions/3.6.5/bin/python3.6 -u -c "import setuptools, tokenize;__file__='/private/var/folders/kz/98sbqxgj04d2vx6prgf92w_wbx535f/T/pip-install-_6lb1k_w/mysqlclient/setup.py';f=getattr(tokenize, 'open', open)(__file__);code=f.read().replace('\r\n', '\n');f.close();exec(compile(code, __file__, 'exec'))" install --record /private/var/folders/kz/98sbqxgj04d2vx6prgf92w_wbx535f/T/pip-record-e5s33jv8/install-record.txt --single-version-externally-managed --compile:
    running install
    running build
    running build_py
    creating build
    creating build/lib.macosx-10.13-x86_64-3.6
    copying _mysql_exceptions.py -> build/lib.macosx-10.13-x86_64-3.6
    creating build/lib.macosx-10.13-x86_64-3.6/MySQLdb
    copying MySQLdb/__init__.py -> build/lib.macosx-10.13-x86_64-3.6/MySQLdb
    copying MySQLdb/compat.py -> build/lib.macosx-10.13-x86_64-3.6/MySQLdb
    copying MySQLdb/connections.py -> build/lib.macosx-10.13-x86_64-3.6/MySQLdb
    copying MySQLdb/converters.py -> build/lib.macosx-10.13-x86_64-3.6/MySQLdb
    copying MySQLdb/cursors.py -> build/lib.macosx-10.13-x86_64-3.6/MySQLdb
    copying MySQLdb/release.py -> build/lib.macosx-10.13-x86_64-3.6/MySQLdb
    copying MySQLdb/times.py -> build/lib.macosx-10.13-x86_64-3.6/MySQLdb
    creating build/lib.macosx-10.13-x86_64-3.6/MySQLdb/constants
    copying MySQLdb/constants/__init__.py -> build/lib.macosx-10.13-x86_64-3.6/MySQLdb/constants
    copying MySQLdb/constants/CLIENT.py -> build/lib.macosx-10.13-x86_64-3.6/MySQLdb/constants
    copying MySQLdb/constants/CR.py -> build/lib.macosx-10.13-x86_64-3.6/MySQLdb/constants
    copying MySQLdb/constants/ER.py -> build/lib.macosx-10.13-x86_64-3.6/MySQLdb/constants
    copying MySQLdb/constants/FIELD_TYPE.py -> build/lib.macosx-10.13-x86_64-3.6/MySQLdb/constants
    copying MySQLdb/constants/FLAG.py -> build/lib.macosx-10.13-x86_64-3.6/MySQLdb/constants
    copying MySQLdb/constants/REFRESH.py -> build/lib.macosx-10.13-x86_64-3.6/MySQLdb/constants
    running build_ext
    building '_mysql' extension
    creating build/temp.macosx-10.13-x86_64-3.6
    clang -Wno-unused-result -Wsign-compare -Wunreachable-code -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes -Dversion_info=(1,3,10,'final',0) -D__version__=1.3.10 -I/usr/local/Cellar/mysql/8.0.11/include/mysql -I/Users/masato-naka/.pyenv/versions/3.6.5/include/python3.6m -c _mysql.c -o build/temp.macosx-10.13-x86_64-3.6/_mysql.o
    _mysql.c:29:10: fatal error: 'my_config.h' file not found
    #include "my_config.h"
             ^~~~~~~~~~~~~
    1 error generated.
    error: command 'clang' failed with exit status 1

    ----------------------------------------
  Rolling back uninstall of mysqlclient
Command "/Users/masato-naka/.pyenv/versions/3.6.5/bin/python3.6 -u -c "import setuptools, tokenize;__file__='/private/var/folders/kz/98sbqxgj04d2vx6prgf92w_wbx535f/T/pip-install-_6lb1k_w/mysqlclient/setup.py';f=getattr(tokenize, 'open', open)(__file__);code=f.read().replace('\r\n', '\n');f.close();exec(compile(code, __file__, 'exec'))" install --record /private/var/folders/kz/98sbqxgj04d2vx6prgf92w_wbx535f/T/pip-record-e5s33jv8/install-record.txt --single-version-externally-managed --compile" failed with error code 1 in /private/var/folders/kz/98sbqxgj04d2vx6prgf92w_wbx535f/T/pip-install-_6lb1k_w/mysqlclient/

```

とりあえず、https://stackoverflow.com/questions/50940302/installing-mysql-python-causes-command-clang-failed-with-exit-status-1-on-macを参考にやってみる。

```
brew unlink mysql # only if installed, causes the next step to fail
brew install mysql-connector-c
vim $(which mysql_config)
```


```
libs="$libs -l "
```
を以下のように

```
libs="$libs -lmysqlclient -lssl -lcrypto"
```
変更する



```
pip install mysqlclient
pip install MySQL-python
brew unlink mysql-connector-c
brew link mysql
```

これでもだめで、最後に、mysql-connector-cをでリンクを上書きしたら・・・

```
brew link --overwrite mysql-connector-c
Linking /usr/local/Cellar/mysql-connector-c/6.1.11... 73 symlinks created
```

入った。。。

理由は完全にはわからず。

誰か、知ってたら教えてください。