pip ERROR: Could not find a version that satisfies the requirement hatchling (from versions: none)

[fedelibre]

I'm trying to build a Qt6 version of Frescobaldi flatpak based on the recent work by @bmjcode, but I get the following error when building qpageview:

========================================================================
Building module qpageview in /var/home/fede/src/flathub.org/org.frescobaldi.Frescobaldi/.flatpak-builder/build/qpageview-2
========================================================================
Updated Git hooks.
Git LFS initialized.
Switched to branch 'qt6'
Running: pip install --prefix=/app .
Processing /run/build/qpageview
  Installing build dependencies ... error
  error: subprocess-exited-with-error

  × pip subprocess to install build dependencies did not run successfully.
  │ exit code: 1
  ╰─> [7 lines of output]
      WARNING: Retrying (Retry(total=4, connect=None, read=None, redirect=None, status=None)) after connection broken by 'NewConnectionError('<pip._vendor.urllib3.connection.HTTPSConnection object at 0x7fcb2b209190>: Failed to establish a new connection: [Errno -3] Temporary failure in name resolution')': /simple/hatchling/
      WARNING: Retrying (Retry(total=3, connect=None, read=None, redirect=None, status=None)) after connection broken by 'NewConnectionError('<pip._vendor.urllib3.connection.HTTPSConnection object at 0x7fcb2b209dd0>: Failed to establish a new connection: [Errno -3] Temporary failure in name resolution')': /simple/hatchling/
      WARNING: Retrying (Retry(total=2, connect=None, read=None, redirect=None, status=None)) after connection broken by 'NewConnectionError('<pip._vendor.urllib3.connection.HTTPSConnection object at 0x7fcb2b20a510>: Failed to establish a new connection: [Errno -3] Temporary failure in name resolution')': /simple/hatchling/
      WARNING: Retrying (Retry(total=1, connect=None, read=None, redirect=None, status=None)) after connection broken by 'NewConnectionError('<pip._vendor.urllib3.connection.HTTPSConnection object at 0x7fcb2b20b550>: Failed to establish a new connection: [Errno -3] Temporary failure in name resolution')': /simple/hatchling/
      WARNING: Retrying (Retry(total=0, connect=None, read=None, redirect=None, status=None)) after connection broken by 'NewConnectionError('<pip._vendor.urllib3.connection.HTTPSConnection object at 0x7fcb2b218150>: Failed to establish a new connection: [Errno -3] Temporary failure in name resolution')': /simple/hatchling/
      ERROR: Could not find a version that satisfies the requirement hatchling (from versions: none)
      ERROR: No matching distribution found for hatchling
      [end of output]

  note: This error originates from a subprocess, and is likely not a problem with pip.
error: subprocess-exited-with-error

× pip subprocess to install build dependencies did not run successfully.
│ exit code: 1
╰─> See above for output.

note: This error originates from a subprocess, and is likely not a problem with pip.

[jeanas]

Flatpak forces the builds to be offline. You probably need to update the output of flatpak-pip-generator or something?

[fedelibre]

Yes, I must install hatchling with flatpak-pip-generator.

[fedelibre]

@jeanas Now I'm pretty sure that hatchling is installed, but I'm getting the same error, as if qpageview was not able to find it and so it tries to download it during build, which is not allowed by flatpak. If the hypothesis is correct, I wonder why qpageview is not able to find hatchling. I see it in the build dir.

Can you please have a look? The test branch is here.

[jeanas]

Missing --no-build-isolation?

[fedelibre]

Missing --no-build-isolation?

Yes, that was it. Thanks! I'm now running Frescobaldi with Qt6,