bug#32390: 26.1; python.el: cleanup font lock buffer after input is sent

[Carlos Pita]

font-locking gets often confused because of unclosed string delimiters.
For example, type " and then press return, start typing in the new input
prompt and the input will be identified as a docstring. It's ok to keep
the font lock buffer while doing multiline edition, but after input is
sent to the underlying process the buffer should be cleaned up so that
each input is independently colorized.

---

In GNU Emacs 26.1 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.22.30)
 of 2018-07-05 built on juergen
Windowing system distributor 'The X.Org Foundation', version 11.0.12000000
Recent messages:
Loading ido-completing-read+...done
Loading paren...done
Loading winner...done
Loading xclip...done
Source file ‘/home/carlos/.emacs.d/elpa/elpy-20180720.155/elpy-shell.el’ newer 
than byte-compiled file
[yas] Prepared just-in-time loading of snippets successfully.
For information about GNU Emacs and the GNU system, type C-h C-a.
ido-read-internal: Command attempted to use minibuffer while in minibuffer
You can run the command ‘run-python’ with M-x r-py RET
Shell native completion is disabled, using fallback

Configured using:
 'configure --prefix=/usr --sysconfdir=/etc --libexecdir=/usr/lib
 --localstatedir=/var --with-x-toolkit=gtk3 --with-xft --with-modules
 'CFLAGS=-march=x86-64 -mtune=generic -O2 -pipe -fstack-protector-strong
 -fno-plt' CPPFLAGS=-D_FORTIFY_SOURCE=2
 LDFLAGS=-Wl,-O1,--sort-common,--as-needed,-z,relro,-z,now'

Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GSETTINGS NOTIFY
ACL GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB TOOLKIT_SCROLL_BARS
GTK3 X11 MODULES THREADS LIBSYSTEMD LCMS2

Important settings:
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Inferior Python

Minor modes in effect:
  pdf-occur-global-minor-mode: t
  diff-auto-refine-mode: t
  pyvenv-mode: t
  shell-dirtrack-mode: t
  compilation-shell-minor-mode: t
  xclip-mode: t
  winner-mode: t
  show-paren-mode: t
  ido-ubiquitous-mode: t
  ido-everywhere: t
  global-company-mode: t
  company-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  column-number-mode: t
  line-number-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message rmc puny rfc822 mml mml-sec epa
derived epg mm-decode mm-bodies mm-encode mail-parse rfc2231 mailabbrev
gmm-utils mailheader sendmail display-line-numbers checkdoc pdf-occur
ibuf-ext ibuffer ibuffer-loaddefs tablist tablist-filter
semantic/wisent/comp semantic/wisent semantic/wisent/wisent
semantic/util-modes semantic/util semantic semantic/tag semantic/lex
semantic/fw mode-local cedet dired dired-loaddefs pdf-isearch let-alist
pdf-misc imenu pdf-tools pdf-view bookmark pp jka-compr pdf-cache
pdf-info tq pdf-util image-mode org-protocol org-element avl-tree
generator org org-macro org-footnote org-pcomplete org-list org-faces
org-entities noutline outline org-version ob-emacs-lisp ob ob-tangle
org-src ob-ref ob-lob ob-table ob-keys ob-exp ob-comint ob-core ob-eval
org-compat org-macs org-loaddefs find-func cal-menu calendar
cal-loaddefs cl-extra yasnippet elec-pair highlight-indentation
flymake-proc flymake warnings help-fns radix-tree help-mode elpy
find-file-in-project ivy delsel colir color ivy-overlay ffap thingatpt
windmove diff-mode easy-mmode elpy-shell pyvenv esh-var esh-io esh-cmd
esh-opt esh-ext esh-proc esh-arg esh-groups eshell esh-module esh-mode
esh-util elpy-profile elpy-django elpy-refactor subr-x python tramp-sh
tramp tramp-compat tramp-loaddefs trampver ucs-normalize shell pcomplete
parse-time format-spec advice json map grep compile comint ansi-color
files-x doom-themes-org doom-tomorrow-night-theme doom-themes
doom-themes-common company-oddmuse company-keywords company-etags etags
xref project company-gtags company-dabbrev-code company-dabbrev
company-files company-capf company-cmake company-xcode company-clang
company-semantic company-eclim company-template company-bbdb xclip
winner ring paren ido-completing-read+ memoize s cus-edit minibuf-eldef
ido gnus nnheader gnus-util rmail rmail-loaddefs rfc2047 rfc2045
ietf-drums mail-utils mm-util mail-prsvr wid-edit company edmacro kmacro
pcase cus-start cus-load finder-inf info package easymenu epg-config
url-handlers url-parse auth-source cl-seq eieio eieio-core cl-macs
eieio-loaddefs password-cache url-vars seq byte-opt gv bytecomp
byte-compile cconv cl-loaddefs cl-lib time-date mule-util tooltip eldoc
electric uniquify ediff-hook vc-hooks lisp-float-type mwheel term/x-win
x-win term/common-win x-dnd tool-bar dnd fontset image regexp-opt fringe
tabulated-list replace newcomment text-mode elisp-mode lisp-mode
prog-mode register page menu-bar rfn-eshadow isearch timer select
scroll-bar mouse jit-lock font-lock syntax facemenu font-core
term/tty-colors frame cl-generic cham georgian utf-8-lang misc-lang
vietnamese tibetan thai tai-viet lao korean japanese eucjp-ms cp51932
hebrew greek romanian slovak czech european ethiopic indian cyrillic
chinese composite charscript charprop case-table epa-hook jka-cmpr-hook
help simple abbrev obarray minibuffer cl-preloaded nadvice loaddefs
button faces cus-face macroexp files text-properties overlay sha1 md5
base64 format env code-pages mule custom widget hashtable-print-readable
backquote dbusbind inotify lcms2 dynamic-setting system-font-setting
font-render-setting move-toolbar gtk x-toolkit x multi-tty
make-network-process emacs)

Memory information:
((conses 16 556542 20830)
 (symbols 48 43787 5)
 (miscs 40 1025 265)
 (strings 32 128269 3450)
 (string-bytes 1 3715198)
 (vectors 16 66976)
 (vector-slots 8 1097024 18728)
 (floats 8 516 401)
 (intervals 56 385 0)
 (buffers 992 16))