tool_cb_wrt: fix no-clobber error handling

When saving a file with --no-clobber, make sure the existing file name
remains set when creating the name fails. In a retry scenario, it comes
back and uses that variable again.

Add test 3036 to verify.

Reported-by: James Fuller
Closes #20939

tests/data/test3036

@@ -0,0 +1,62 @@
+<?xml version="1.0" encoding="US-ASCII"?>
+<testcase>
+<info>
+<keywords>
+-O
+-J
+--output-dir
+--retry
+--no-clobber
+</keywords>
+</info>
+# Server-side
+<reply>
+<data nocheck="yes">
+HTTP/1.1 200 OK
+Content-Length: 6
+Connection: close
+Content-Disposition: inline; filename="MMM%TESTNUMBERMMM"
+Content-Type: text/html
+
+-foo-
+</data>
+</reply>
+
+# Client-side
+<client>
+<server>
+http
+</server>
+<features>
+http
+</features>
+<name>
+--no-clobber, --retry and --output-dir identifying a file
+</name>
+<command option="no-output">
+http://%HOSTIP:%HTTPPORT/ --no-clobber --output-dir %LOGDIR/present -OJ --retry 1 --retry-all-errors
+</command>
+<file name="%LOGDIR/present">
+present
+</file>
+</client>
+
+<verify>
+<protocol crlf="headers">
+GET / HTTP/1.1
+Host: %HOSTIP:%HTTPPORT
+User-Agent: curl/%VERSION
+Accept: */*
+
+GET / HTTP/1.1
+Host: %HOSTIP:%HTTPPORT
+User-Agent: curl/%VERSION
+Accept: */*
+
+</protocol>
+# it fails because it cannot create the output file
+<errorcode>
+23
+</errorcode>
+</verify>
+</testcase>