FAQ: wip

Documentation/FAQ.md

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+# Frequently Answered Questions
+
+## Table of Contents
+
+  * [Why did it rewrite commit hashes?](#why-did-it-rewrite-commit-hashes)
+  * [Why did it rewrite more commit hashes than I expected?](#why-did-it-rewrite-more-commit-hashes-than-i-expected)
+  * [Why did it rewrite other branches too?](#why-did-it-rewrite-other-branches-too)
+  * [Help! Can I recover or undo the filtering?](#help-can-i-recover-or-undo-the-filtering)
+  * [What kinds of problems does git-filter-repo not try to solve?](#What-kinds-of-problems-does-git-filter-repo-not-try-to-solve)
+
+
+## Why did it rewrite commit hashes?
+## Why did it rewrite more commit hashes than I expected?
+## Why did it rewrite other branches too?
+## Help! Can I recover or undo the filtering?
+## What kinds of problems does git-filter-repo not try to solve?
+
+# FIXME
+
+## What kinds of problems does git-filter-repo not try to solve?
+
+  * Filtering history but magically keeping the same commit IDs
+  * Bidirectional development between filtered and unfiltered repository (josh)
+  * Filtering based on the difference (a.k.a. patch or change) between commits (rebase)
+  * Conversion between different version control systems (reposurgeon)
+  * Having two people filter their clone of the repository (with the same
+    filtering command) and getting the same new commit IDs
+
+## Help! Can I recover or undo the filtering?
+
+  * https://github.com/newren/git-filter-repo/issues/606
+
+## Why did it rewrite other branches too?
+
+  * https://github.com/newren/git-filter-repo/issues/527
+
+How do I see what was removed?
+
+  * Give answer in terms of `git rev-list --objects --all` in both a
+    separate fresh clone from before the rewrite and in the repo where
+    the rewrite was done.  Then find the objects that exist in the old
+    but not the new.
+
+Why are the commit hashes changing?
+
+  * https://github.com/newren/git-filter-repo/issues/607
+  * Multiple reasons:
+    * Any commit you change must get a new hash
+    * Any commit who has a changed commit as a parent or earlier ancestor
+      must change
+    * commit and tag signatures
+    * git-fast-export and git-fast-import canonicalize history in various
+      ways...
+
+Handling corruption?
+
+  git fsck throws warnings/errors=>git-filter-repo may not parse the objects...