Fix infinite loop in install script

[christian-stephen]

Checklist

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• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have checked for similar issues and haven't found anything relevant.
• This is not a security issue (which should be reported here: https://circleci.com/security/)
• I have read Contribution Guidelines.

Changes

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• Fix the infinite loop in the install script by renaming the install function in the script to install_circleci, so that it no longer has a name collision with the system's install command

Rationale

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Per this issue and comment, a recently merged PR appears to have introduced an infinite loop in the install script because of a name collision with the install function and the system's install command. When piping the script into bash, it loops indefinitely as the install function recursively calls itself:

Starting installation.
Installing CircleCI CLI v0.1.26646
Installing to /usr/local/bin
Starting installation.
Installing CircleCI CLI v0.1.26646
Installing to /usr/local/bin
Starting installation.
Installing CircleCI CLI v0.1.26646
^C⏎

Considerations

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N/A

Screenshots

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N/A

[christian-stephen]

Closing in favour of #943