docs: say what the count counted, and why these two are not terminal (#1215) - #1245

…ommandprompt#1215)

`arrow_import.sh` explains why it does not use `pgc_skip` and said "THE OTHER 29
pyarrow SUITES USE" it. Recounted, the number is 25: the suites whose source,
with comments stripped, calls `pgc_skip` with the pyarrow capability. 29 is not
reproducible now under any population except one counting `lib.sh`, where the
function is defined, plus three suites that gate on other capabilities and name
pyarrow only in prose. Whether it was right when written is unknown, and the
comment now says that rather than carrying a bare number.

The recount is a worked example of the defect it fixes. The first attempt
returned 26, because searching `arrow_import.sh` for `pgc_skip` matches the
sentence explaining why it does not call `pgc_skip`. Comments stripped, that
file scores 0.

`native_parquet_schema.sh` and `parquet_nested_import.sh` decline arm by arm
rather than being terminal, as `arrow_import.sh` does, but unlike it said
nothing about why. A reader arriving at either had no way to tell a deliberate
deviation from an oversight. Both now carry the measurement that justifies it:
29 of 35 arms and 5 of 7 need no pyarrow, the name set is identical with and
without it, and both runs still exit 0.

Comments only. No test changed, no check added, no behaviour changed.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MpajdQbkVJ9ey1XyYHcikP

…ompt#1215)

The previous version gave three rows and said 29 reproduces "by the
`import pyarrow` reading and by that reading only -- naming pyarrow anywhere
gave 34 even then". True, and it omitted the predicate that actually separates
them, which is comment stripping.

Measured four ways at f738dd4 and today, same exclusions:

                                     at f738dd4   today
    names pyarrow anywhere               34          35
    names pyarrow in CODE                29          30
    runs `import pyarrow` in code        29          30
    imports it AND calls pgc_skip        25          25

The five in the 34/29 gap name pyarrow only to say they do NOT use it:
native_parquet_stack and parallel_export_parquet hand-craft their fixtures, and
avro_manifest, iceberg_deletes and iceberg_name_mapping gate on other
capabilities. Which is the same house-style trap as searching this file for
`pgc_skip` and matching the sentence that says why not to use it.

Three rows invite the reader to guess which "names pyarrow" means. Two
reviewers guessing differently is how 34 and 29 were taken for a disagreement
when both were right about different populations. @jdatcmd asked for the fourth
row and the predicate on each.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MpajdQbkVJ9ey1XyYHcikP