[credential.helper] unexpectedly save credential to multiple credential files

> 1. git config --global credential.helper store
> 2. cd to a local repository directory, git config credential.helper
> store --file ./my_cred
> 3. execute some git command which need credential like git ls-remote
> 4. input my username & password, command done.
> 
> As the result, **BOTH** the ./my_cred and ~/.git-credentials will save
> the credentials I just input. But, shouldn't the local config override
> the global ones, and only the ./my_cred should save it?

> On Fri, Nov 11, 2016 at 04:10:55PM +0800, Qi Nark wrote:
>
>> 1. git config --global credential.helper store
>> 2. cd to a local repository directory, git config credential.helper
>> store --file ./my_cred
>> 3. execute some git command which need credential like git ls-remote
>> 4. input my username & password, command done.
>>
>> As the result, **BOTH** the ./my_cred and ~/.git-credentials will save
>> the credentials I just input. But, shouldn't the local config override
>> the global ones, and only the ./my_cred should save it?
>
> No, that's the expected result. The set of credential helpers form a
> list, and each is run in turn. From "git help credentials":
>
>   If there are multiple instances of the credential.helper configuration
>   variable, each helper will be tried in turn, and may provide a
>   username, password, or nothing. Once Git has acquired both a username
>   and a password, no more helpers will be tried.
>
> That's talking about lookup, but the same principle applies to storage.
> But you may also find the paragraph below helpful:
>
>   If credential.helper is configured to the empty string, this resets
>   the helper list to empty (so you may override a helper set by a
>   lower-priority config file by configuring the empty-string helper,
>   followed by whatever set of helpers you would like).
>
> Note that the "reset" behavior was introduced in git v2.9.0, so you'll
> need at least that version.
>
> -Peff