Ignore Sync errors on pipes when doing CheckAttributeReader.CheckPath, fix the hang of git cat-file (#17096)

* Ignore Sync errors on pipes when doing `CheckAttributeReader.CheckPath`

* apply env patch

* Drop the Sync and fix a number of issues with the Close function

Signed-off-by: Andrew Thornton <art27@cantab.net>

* add logs for DBIndexer and CheckPath

* Fix some more closing bugs

Signed-off-by: Andrew Thornton <art27@cantab.net>

* Add test case for language_stats

Signed-off-by: Andrew Thornton <art27@cantab.net>

* Update modules/indexer/stats/db.go

Co-authored-by: Lauris BH <lauris@nix.lv>

Co-authored-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: Lauris BH <lauris@nix.lv>
Co-authored-by: 6543 <6543@obermui.de>

modules/git/tests/repos/language_stats_repo/hooks/applypatch-msg.sample

@@ -0,0 +1,15 @@
+#!/bin/sh
+#
+# An example hook script to check the commit log message taken by
+# applypatch from an e-mail message.
+#
+# The hook should exit with non-zero status after issuing an
+# appropriate message if it wants to stop the commit.  The hook is
+# allowed to edit the commit message file.
+#
+# To enable this hook, rename this file to "applypatch-msg".
+
+. git-sh-setup
+commitmsg="$(git rev-parse --git-path hooks/commit-msg)"
+test -x "$commitmsg" && exec "$commitmsg" ${1+"$@"}
+: