i386 Subsurface AppImage

[probono]

Trying to build in an i386 schroot using
https://github.com/probonopd/AppImages/blob/multiarch/recipes/subsurface.sh
but keep getting "Unsupported architecture".

I am almost certain I am doing something stupid but cannot spot it.

Here is the relevant build log:

+ PKG_CONFIG_PATH=/mnt/Subsurface/Subsurface.AppDir/usr/lib/pkgconfig:
+ echo Building in /mnt/Subsurface, installing in
/mnt/Subsurface/Subsurface.AppDir/usr
Building in /mnt/Subsurface, installing in /mnt/Subsurface/Subsurface.AppDir/usr
+ '[' Linux = Darwin ']'
+ cd /mnt/Subsurface
+ '[' '!' -d libgit2 ']'
+ cd libgit2
+ git fetch origin
+ git checkout v0.23.1
HEAD is now at f6dedf2... Bump version to v0.23.1
+ mkdir -p build
+ cd build
+ cmake -DCMAKE_INSTALL_PREFIX=/mnt/Subsurface/Subsurface.AppDir/usr
-DCMAKE_BUILD_TYPE=Release -DBUILD_CLAR=OFF ..
-- The C compiler identification is GNU
-- Check for working C compiler: /usr/bin/gcc
-- Check for working C compiler: /usr/bin/gcc -- works
-- Found OpenSSL:
/usr/lib/i386-linux-gnu/libssl.so;/usr/lib/i386-linux-gnu/libcrypto.so
(found version "1..1")
-- Could NOT find HTTP_Parser (missing:  HTTP_PARSER_INCLUDE_DIR
HTTP_PARSER_LIBRARY)
-- http-parser was not found or is too old; using bundled 3rd-party sources.
CMake Error at CMakeLists.txt:489 (MESSAGE):
  Unsupported architecture

If you can spot the mistake, please let me know. Thanks.