Bug#913636: context.postinstall "luatools --make cont-en" hangs, "attempt to call upvalue 'isfile' (a nil value)"

[Jonathon Fernyhough <jonathon.fernyhough@york.ac.uk>]

Package: context
Version: 2018.04.04.20180416-1
Severity: grave
Justification: renders package unusable

Dear Maintainer,

When installing context with texlive-binaries=2018.20181104.49075-1 the
context.postinst task `luatools --make cont-en` fails to complete correctly
making package installation hang indefinitely:

$ luatools --make cont-en

resolvers       | formats | using format path '/var/lib/texmf/luatex-cache/context/b47c3d3cee7cb6c86268d0595268c442/formats/luatex'
resolvers       | resolving | using given filetype 'tex'
resolvers       | methods | resolving, method 'concatinators', how 'tag', tag 'file'
resolvers       | resolving | remembering file 'cont-en.mkiv' using hash 'tex::cont-en.mkiv'
resolvers       | formats | using tex source file '/usr/share/texmf/tex/context/base/mkiv/cont-en.mkiv'
resolvers       | resolving | checking qualified name '/usr/share/texmf/tex/context/base/mkiv/cont-en.lus'
resolvers       | resolving | using given filetype 'tex'
resolvers       | resolving | remembering file '/usr/share/texmf/tex/context/base/mkiv/cont-en.lus' using hash 'tex::/usr/share/texmf/tex/context/base/mkiv/cont-en.lus'
resolvers       | resolving | remembering file '/usr/share/texmf/tex/context/base/mkiv/context.lus' using hash 'tex::/usr/share/texmf/tex/context/base/mkiv/context.lus'
resolvers       | formats | executing runner 'make luatex format': luatex --ini  --lua=/usr/share/texmf/tex/context/base/mkiv/luat-cod.lua /usr/share/texmf/tex/context/base/mkiv/cont-en.mkiv  \dump This is LuaTeX, Version 1.09.0 (TeX Live 2019/dev/Debian)  (INITEX)
 system commands enabled.
error in callback: /usr/share/texmf/tex/context/base/mkiv/luat-cod.lua:166: attempt to call upvalue 'isfile' (a nil value)
.
<insert>  
 
<*> ...hare/texmf/tex/context/base/mkiv/cont-en.mkiv 
                                                  dump
? 


-- System Information:
Debian Release: buster/sid
  APT prefers unstable
  APT policy: (500, 'unstable')
Architecture: amd64 (x86_64)

Kernel: Linux 4.18.0-18.1-liquorix-amd64 (SMP w/16 CPU cores; PREEMPT)
Locale: LANG=C, LC_CTYPE=en_GB.UTF-8 (charmap=ANSI_X3.4-1968) (ignored: LC_ALL set to C), LANGUAGE=en_GB: (charmap=ANSI_X3.4-1968) (ignored: LC_ALL set to C)
Shell: /bin/sh linked to /bin/dash
Init: unable to detect

Versions of packages context depends on:
ii  lmodern           2.004.5-5
ii  ruby              1:2.5.1
ii  tex-common        6.10
ii  tex-gyre          20180621-2
ii  texlive-base      2018.20181106-1
ii  texlive-binaries  2018.20181104.49075-1
ii  texlive-metapost  2018.20181106-1

Versions of packages context recommends:
pn  context-modules           <none>
pn  fonts-freefont            <none>
ii  fonts-gfs-artemisia       1.1-5
ii  fonts-gfs-baskerville     1.1-5
pn  fonts-gfs-bodoni-classic  <none>
ii  fonts-gfs-didot           1.1-6
pn  fonts-gfs-didot-classic   <none>
pn  fonts-gfs-gazis           <none>
ii  fonts-gfs-neohellenic     1.1-6
ii  fonts-gfs-olga            1.1-5
ii  fonts-gfs-porson          1.1-6
ii  fonts-gfs-solomos         1.1-5
pn  fonts-gfs-theokritos      <none>
ii  fonts-sil-gentium         20081126:1.03-2

Versions of packages context suggests:
pn  context-doc-nonfree  <none>
pn  context-nonfree      <none>
pn  fontforge            <none>
pn  libxml-parser-perl   <none>
pn  perl-tk              <none>

-- no debconf information