Had to also bump ubuntu version 18.04->20.04,
as was getting errors running the self-compiled pyinstaller otherwise (weird...):
```
from .utils.git import get_repo_revision
ModuleNotFoundError: No module named 'PyInstaller.utils'
```
(similar to https://github.com/pyinstaller/pyinstaller/issues/4403 )
-----
Note re appimage: when trying to compile python 3.8.x on ubuntu 16.04, I am getting:
./Modules/posixmodule.c: In function ‘os_copy_file_range_impl’:
./Modules/posixmodule.c:10351:15: error: implicit declaration of function ‘copy_file_range’ [-Werror=implicit-function-declaration]
ret = copy_file_range(src, p_offset_src, dst, p_offset_dst, count, flags);
This is because ubuntu 16.04 has too old glibc.
If there is a collision between a branch name and a commit hash, git
will choose the branch, even if the full 40-hex-long commit hash is
given. GitHub disallows branches/tags with such a name but git itself
does not. By adding the `^{commit}` syntax sugar after a ref name,
we can tell git that we want the commit hash to be preferred,
and hence we don't need to trust GitHub (only git).
see https://security.stackexchange.com/questions/225411/
All (incl indirect) dependencies are already listed in deterministic-build/requirements*.txt.
This option makes it easier to manually rm a dependency from that list for e.g. testing.
Slightly reduces file size, improves build speed and makes build more
reproducible.
The .comment section contained GCC version information which could cause
different build output from just a minor update in GCC. The information is not
needed so we strip this.
The strip command was invoked using xargs, spawning a new process for each file.
This is inefficient as xargs can correctly run the strip command with multiple
file names.
-----
taken from https://github.com/Electron-Cash/Electron-Cash/commit/43aaf9572f822b977ecffe68f9cce428e5d27c18
On Ubuntu host, build succeeded; but e.g. on Manjaro host, it failed with:
```
./build.sh: line 233: /opt/electrum/contrib/build-linux/appimage/../../../contrib/build-linux/appimage/.cache/appimage/appimagetool: No such file or directory
```
This slightly increases the AppImage size but allows us to be more
compatible with older distributions.
-----
taken from Electron-Cash/Electron-Cash@96644acd6f
It warns about scripts being installed in a location that is not on the
path, but that is inconsequential as they are not used.
-----
taken from Electron-Cash/Electron-Cash@9a29017c5d
When building in docker on macOS, python builds with .exe extension
because the case insensitive file system of macOS leaks into docker.
This causes the build to result in a different output on macOS compared
to Linux. We simply patch sysconfigdata to remove the extension.
Some more info: https://bugs.python.org/issue27631
There are a lot of dupliacted files, testing files and unused libraries
present in the AppImage. Removing these reduces the AppImage size
significantly.
-----
taken from Electron-Cash/Electron-Cash@cff5fb1289
ThomasV