Use /etc/phenix/store.bdb by default when root, even if root was obtained via sudo

[activeshadow]

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Originally created by @activeshadow on Wed, 20 Jan 2021 18:06:02 GMT

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Right now, phenix checks to see if the SUDO_USER env variable is set, and if so it uses the store local to that user. However, SUDO_USER is set even when a user is currently root via sudo su.

The hack way to get around this is to run su - after running sudo su, which unsets the SUDO_USER env variable.

In the code, we should also check the SUDO_COMMAND env variable and only use the store local to the SUDO_USER if the command is for the phenix executable. When someone sudo's to root, the SUDO_COMMAND will be set to something like /bin/su.