Retain with=FALSE in j=lit:var cases

[MichaelChirico]

For #6671 (not closing because we should wait for the revdep checker to confirm the fix).

This also fixes a mistake where is.name(e[[1]]) was used. e[[1]] is always : in this case, and therefore is always a name. e[[2]] and e[[3]] are the arguments to :, which is what we really want to inspect.

The added tests help cover the mistaken logic there too.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.61%. Comparing base (70c64ac) to head (dfde60a).
Report is 3 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #6700   +/-   ##
=======================================
  Coverage   98.61%   98.61%           
=======================================
  Files          79       79           
  Lines       14553    14553           
=======================================
  Hits        14352    14352           
  Misses        201      201           

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[github-actions]

Generated via commit dfde60a

Download link for the artifact containing the test results: ↓ atime-results.zip

Task	Duration
R setup and installing dependencies	4 minutes and 41 seconds
Installing different package versions	7 minutes and 38 seconds
Running and plotting the test cases	2 minutes and 15 seconds

[tdhock]

lgtm thanks