Remove unnessesary : from shellenv cmd

[Jxck]

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[gromgit]

It may not do anything useful on macOS, but it doesn't hurt, as far as I can tell.

On Linux, however, it has a very useful purpose. From the manpath(5) man page:

SEARCH PATH
[...]
If the value of $MANPATH starts with a colon, then the default search path is added at its start. If the value of $MANPATH ends with a colon, then the default search path is added at its end. If the value of $MANPATH contains a double colon (::), then the default search path is inserted in the middle of the value, between the two colons.

[Bo98]

Yes, this is intentional. We should maybe make that more obvious somehow since this has been asked before.

[MikeMcQuaid]

Yes, this is intentional. We should maybe make that more obvious somehow since this has been asked before.

@Bo98 A comment in the source perhaps?