Drop an unreachable newline guard

'read' without '-d' stops at the first newline, so EXCMD never holds one, and a
newline inside the ':execute' string stays in the sandbox anyway.

bin/tagpreview.sh

@@ -34,9 +34,7 @@ fi
 # as soon as an entry is highlighted. Sandboxed as a builtin tag jump is, so that
 # it cannot run a shell command or touch a file. ':sandbox' on its own only covers
 # the command up to the first '|', so hand the whole address to ':execute' as a
-# string literal, doubling the quotes in it. A newline would end that line and
-# leave the rest outside the sandbox, and no tags file holds one, so drop them
-EXCMD=${EXCMD//$'\n'/ }
+# string literal, doubling the quotes in it
 EXCMD_LITERAL=${EXCMD//\'/\'\'}
 CENTER="$("${VIMNAME}" -R -i NONE -u NONE -e -m -s "${FILE}" \
               -c "set nomagic" \