`eshell/clear' is implemented by sending a series of blank lines,
which is not a useful thing to have in the history.
* lisp/eshell/em-hist.el (eshell-input-filter-default): Use
`string-blank-p' which does check for newlines (even though newlines
have comment-end syntax, not whitespace syntax class).
* lisp/eshell/esh-mode.el (eshell/clear): Remove
`eshell-add-to-history' from `eshell-input-filter-functions' while
sending the blank lines. This change is needed to solve the bug if
the user customizes `eshell-input-filter' to something that doesn't
filter newlines.
4676542062