`I()` protection lost when subsequent `req_url_query()` calls re-parse the URL

[Brar]

When a value is wrapped in I() to prevent encoding in req_url_query(), the protection is silently lost if any subsequent req_url_query() call is chained on the same request. The second call re-parses and re-encodes the entire URL, defeating I(). This makes I() order-dependent in a way that isn't documented — it only works if no further req_url_query() calls follow.

Minimal repro

library(httr2)

# I() works when it's the only/last req_url_query() call
req1 <- request("https://example.com/api") |>
  req_url_query(param = I("abc;def;ghi"))
req1$url
#> "https://example.com/api?param=abc;def;ghi"
# ✅ Semicolons preserved

# But a subsequent req_url_query() re-parses the URL and re-encodes them
req2 <- req1 |>
  req_url_query(other = "xyz")
req2$url
#> "https://example.com/api?param=abc%3Bdef%3Bghi&other=xyz"
# ❌ Semicolons encoded as %3B despite I()

Verified output

$ Rscript --vanilla -e "library(httr2); req <- req_url_query(request('https://example.com/api'), param = I('abc;def;ghi')); cat(req[['url']], '\n')"
https://example.com/api?param=abc;def;ghi

$ Rscript --vanilla -e "library(httr2); req <- req_url_query(request('https://example.com/api'), param = I('abc;def;ghi')); req <- req_url_query(req, other = 'xyz'); cat(req[['url']], '\n')"
https://example.com/api?param=abc%3Bdef%3Bghi&other=xyz

Expected behavior

I() should prevent encoding of the value regardless of whether additional req_url_query() calls follow.

Actual behavior

The AsIs protection is silently lost when any subsequent req_url_query() call re-parses and rebuilds the URL.

Session info

packageVersion("httr2")
#> [1] '1.2.2'