The length of the required abbreviation grows over time, while content you put in commit messages sticks around. Meaning a commit done in year 2005 may have gotten away with "Fixes: abcd" and was unambiguous at that time, whereas after 20 years of growth, there could now be multiple other commits with that prefix.
By that logic, any length of abbreviation will eventually fail if stored for a long time, those abbreviations should be seen as temporary for user interaction only. For the "Fixes:" footer they should have gone with full hash, it's hidden away in the footer so it doesn't disrupt anyone. Aanyone interacting with it will double click to copy it regardless if it is 8 or 40 characters long. Abbreviating it simply adds no value.
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The length of the required abbreviation grows over time, while content you put in commit messages sticks around. Meaning a commit done in year 2005 may have gotten away with "Fixes: abcd" and was unambiguous at that time, whereas after 20 years of growth, there could now be multiple other commits with that prefix.
By that logic, any length of abbreviation will eventually fail if stored for a long time, those abbreviations should be seen as temporary for user interaction only. For the "Fixes:" footer they should have gone with full hash, it's hidden away in the footer so it doesn't disrupt anyone. Aanyone interacting with it will double click to copy it regardless if it is 8 or 40 characters long. Abbreviating it simply adds no value.
Well a fix has to be for a parent commit so future commits and future growth aren't nearly as important.