P. J. created
Many software projects include a changelog (normally a file called "CHANGES") in their source tree. I see acl keeps a changelog in doc/CHANGES , and the Debian package also installs this file to /usr/share/doc/libacl1/changelog.gz on your system (/usr/share/doc/$PACKAGE/ is a good place to look for such documentation). Debian packages also have their own changelogs (debian/changelog in the source package). You can find the changelog for libacl1 packaging on Debian's package database service or at /usr/share/doc/libacl1/changelog.Debian.gz on your system.