fix(shell): remove test harness pipe hazards (#1106)

Co-authored-by: f10-coder <[email protected]>

packages/mosaic/framework/tools/git/test-issue-comment-readback.sh

@@ -280,7 +280,10 @@ print("201")
 print(json.dumps(record))
 PY
 )
-    write_response "$(printf '%s' "$result" | head -n1)" "$(printf '%s' "$result" | tail -n +2)"
+    response_status="${result%%$'\n'*}"
+    response_body=""
+    [[ "$result" == *$'\n'* ]] && response_body="${result#*$'\n'}"
+    write_response "$response_status" "$response_body"
 elif [[ "$method" == "GET" && "$path" == "$ISSUE_COMMENT_API_BASE"/issues/comments/* ]]; then
     result=$(ISSUE_COMMENT_GET_ID="${path##*/}" python3 - <<'PY'
 import json
@@ -299,7 +302,10 @@ else:
     print(json.dumps(match))
 PY
 )
-    write_response "$(printf '%s' "$result" | head -n1)" "$(printf '%s' "$result" | tail -n +2)"
+    response_status="${result%%$'\n'*}"
+    response_body=""
+    [[ "$result" == *$'\n'* ]] && response_body="${result#*$'\n'}"
+    write_response "$response_status" "$response_body"
 else
     echo "Unexpected curl request: $method $url" >&2
     exit 97