chicken-install fails installing eggs when encountering truncated/empty .egg-info files

[Vasilij Schneidermann]

When installing eggs with {{chicken-install}}, it checks for already installed files by walking over all installed .egg-info files with {{matching-installed-files}} and {{load-egg-info}}. If one of these .egg-info files cannot be {{read}}, the whole installation process aborts. A similar phenomenon applies to {{chicken-uninstall}} with {{remove-extension}} and {{load-egg-info}}. The user must therefore manually delete all affected egg files to have a working set of eggs again.

Two proposals:

• Considering that the {{egg-info}} files are some sort of database, there should be a consistency check to ensure their integrity when installing/removing eggs.
• If installing/removing eggs comes across a malformed {{egg-info}} file, it should display a warning and skip processing it. Maybe even suggest a manual uninstallation.

As for why these truncations happen, no idea. I've observed one such case with egg installation of srfi-27 and math on Windows, presumably due to maximum command length limits.