De-duplicate at the first '.' following the filename, not the path

Fix the fix to issue #380.

Thanks for letting me know Keyop.
14 jobs for master in 9 minutes and 38 seconds (queued for 12 seconds)
Status Job ID Name Coverage
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passed #33870
FreeBSD
jsdoor-freebsd

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passed #33871
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jsdoor-linux

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passed #33873
FreeBSD
jsdoor-windows

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passed #33865
FreeBSD
sbbs-freebsd

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passed #33860
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sbbs-linux

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passed #33863
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sbbs-windows

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passed #33872
FreeBSD
sexpots-freebsd

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sexpots-linux

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sexpots-windows

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passed #33868
FreeBSD
syncdraw-freebsd

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syncdraw-linux

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FreeBSD
syncterm-freebsd

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passed #33862
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syncterm-linux

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passed #33867
FreeBSD
syncterm-windows

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