Do not include symbol on lhs of := in othervars

[renkun-ken]

This is an attempt to fix #2326.

[MichaelChirico]

Hi Kun, thanks!

Please be sure to include tests and make sure the updated package compiles and that test.data.table() runs without error -- in particular I think it's likely there's a reason the LHS was included in othervars, which should be covered by another test, so this bug fix will have to allow that use case to continue to function.

See here:
https://github.com/Rdatatable/data.table/blob/master/Contributing.md

[mattdowle]

Hi Kun,
Thanks from me too. In case you are on Ubuntu, I recently added my dev cycle in the cc.R file in the project root. That's how to easily make changes and run all tests, at least how I do it. Once that is passing you can do the longer R CMD build and R CMD check before pushing the pull request. If you are on Mac or Windows then cc.R will likely need some tweaking.
Hope that helps,
Matt

[renkun-ken]

Thanks for reminding! I'm working on macOS at the moment (or may turn to Ubuntu if necessary) and will need a little while to get familiar with data.table's testing and find out what breaks previous test cases.

[codecov-io]

Codecov Report

Merging #2329 into master will increase coverage by 0.03%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #2329      +/-   ##
==========================================
+ Coverage   90.92%   90.96%   +0.03%     
==========================================
  Files          61       61              
  Lines       11800    11804       +4     
==========================================
+ Hits        10729    10737       +8     
+ Misses       1071     1067       -4

Impacted Files	Coverage Δ
R/data.table.R	97.42% <100%> (ø)	⬆️
src/forder.c	94.47% <0%> (+0.52%)	⬆️

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[mattdowle]

Great PR!! Thanks!

[MichaelChirico]

Nice @renkun-ken! The PR process can be a steep learning curve, glad you could navigate it 🤓