bug#38176: 27.0.50; pdf-tools images do not display

[Óscar Fuentes]

With pdf-tools installed (version 0.90 available on Melpa-stable), visit
a multi-page PDF document. Press <Space> until the end of the first page
is visible, press <Space> again. Normally the second page would be
displayed, but the window shows an empty area. Press <Down> cursor
arrow, the image of the second page turns visible. Press C-x 3 then C-x
1 and the image disappears.

On my setup, after performing the steps described above, the vertical
lines which pdf-tools surrounds the image with are drawn on the
minibuffer window.

Also, on one occasion, Emacs entered what seemed an unresponsive state
with 100% cpu utilization. After attaching gdb the stack frame was:

(gdb) bt
#0  0x0000563f84a110b8 in add_row_entry (row=0x563f9b8200a0)
    at ../../emacs/src/dispnew.c:4268
#1  0x0000563f84a16910 in scrolling_window (tab_line_p=<optimized out>, 
w=0x5b9b)
    at ../../emacs/src/dispnew.c:4491
#2  0x0000563f84a16910 in update_window
    (w=w@entry=0x563f86c70b40, force_p=force_p@entry=true) at 
../../emacs/src/dispnew.c:3573
#3  0x0000563f84a17301 in update_window_tree
    (w=w@entry=0x563f86c70b40, force_p=force_p@entry=true) at 
../../emacs/src/dispnew.c:3330
#4  0x0000563f84a1754b in update_frame (f=f@entry=0x563f8b6a7700, 
force_p=<optimized out>, 
    force_p@entry=false, inhibit_hairy_id_p=inhibit_hairy_id_p@entry=false)
    at ../../emacs/src/dispnew.c:3219
#5  0x0000563f84a4b485 in redisplay_internal () at ../../emacs/src/xdisp.c:15669
#6  0x0000563f84ae120f in read_char
    (commandflag=1, map=XIL(0x563f9475d8e3), prev_event=XIL(0), 
used_mouse_menu=0x7ffdbf70da1b, end_time=0x0) at ../../emacs/src/keyboard.c:2488
#7  0x0000563f84ae3b6a in read_key_sequence
    (keybuf=<optimized out>, prompt=XIL(0), dont_downcase_last=<optimized out>, 
can_return_switch_frame=true, fix_current_buffer=true, 
prevent_redisplay=<optimized out>)
    at ../../emacs/src/keyboard.c:9536
#8  0x0000563f84ae520c in command_loop_1 () at ../../emacs/src/lisp.h:1032
#9  0x0000563f84b4a377 in internal_condition_case
    (bfun=bfun@entry=0x563f84ae5030 <command_loop_1>, 
handlers=handlers@entry=XIL(0x90), hfun=hfun@entry=0x563f84adc2f0 <cmd_error>) 
at ../../emacs/src/eval.c:1355
#10 0x0000563f84ad7154 in command_loop_2 (ignore=ignore@entry=XIL(0))
    at ../../emacs/src/lisp.h:1032
#11 0x0000563f84b4a2d1 in internal_catch
    (tag=tag@entry=XIL(0xcc30), func=func@entry=0x563f84ad7130 
<command_loop_2>, arg=arg@entry=XIL(0)) at ../../emacs/src/eval.c:1116
#12 0x0000563f84ad70fb in command_loop () at ../../emacs/src/lisp.h:1032
#13 0x0000563f84adbf06 in recursive_edit_1 () at ../../emacs/src/keyboard.c:714
#14 0x0000563f84adc232 in Frecursive_edit () at ../../emacs/src/keyboard.c:786
#15 0x0000563f84a0e866 in main (argc=2, argv=<optimized out>)

Lisp Backtrace:
"redisplay_internal (C function)" (0x0)



In GNU Emacs 27.0.50 (build 3, x86_64-pc-linux-gnu, X toolkit)
 of 2019-11-09 built on sky
Repository revision: f8284f1e408b38e6a3c0e2a1d5a465fefac6800a
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12004000
System Description: Debian GNU/Linux bullseye/sid