Hide non-deterministic data from from traceback in tests

tests/basic/TF_RUN

         inv_xpath:o_err)
             echo 'Invalid expression'
             echo 'Traceback (most recent call last):'
-            echo '  File "/usr/libexec/shellfu-bash-pxpath/pxpath", line 54, in <module>'
+            echo '  File _SOME_FILE_, line _SOME_LINE_, in <module>'
             echo '    matches = context.xpathEvalExpression(expr)'
-            echo '  File "/usr/lib64/python2.7/site-packages/libxml2.py", line 7346, in xpathEvalExpression'
+            echo '  File _SOME_FILE_, line _SOME_LINE_, in xpathEvalExpression'
             echo "    if ret is None:raise xpathError('xmlXPathEvalExpression() failed')"
             echo 'libxml2.xpathError: xmlXPathEvalExpression() failed'
             ;;
 
 runtest() {
     local xpath
+    local r_es=0
     mkdir -p "test" "result/$name"
     mkxml > "test.xml"
     xpath=$(mka xpath)
         io_adir)        pxpath "$xpath" oracle ;;
         io_pipe)        <"test.xml" pxpath "$xpath" - ;;
         *)  pxpath  "$xpath" "test.xml" ;;
-    esac
+    esac >out.cache 2>err.cache; r_es=$?
+    cat out.cache
+    <err.cache sed '
+        /^  File /s/File ".*",/File _SOME_FILE_,/
+        /^  File /s/line [1-9][0-9]*,/line _SOME_LINE_,/
+    ' >&2
+    return $r_es
 }
 
 tf_do_subtest() {