build: Check .idx and .rev files

Add new tests to verify the idx and rev files. Note that two files are being ignored,
one is for a sha256 repository, which unfortunately the upstream git does not seem to
support.

The second ignored pack file does not have an idxfile, hence it makes no sense to verify
it nor to generate a rev file for that pack file.

Signed-off-by: Paulo Gomes <pjbgf@linux.com>

Author: pjbgf

.github/workflows/test.yml

@@ -33,3 +33,21 @@ jobs:
 
     - name: Test
       run: make test
+
+    - name: Check index files
+      shell: bash
+      run: |
+        ls data/pack-*.pack | \
+        grep -v 407497645643e18a7ba56c6132603f167fe9c51c00361ee0c81d74a8f55d0ee2 | \
+        grep -v ee4fef0ef8be5053ebae4ce75acf062ddf3031fb | \
+        xargs -I{} git verify-pack -v {}
+
+    - name: Re-generate reverse index files
+      shell: bash
+      run: |
+        ls data/pack-*.pack | \
+        grep -v 407497645643e18a7ba56c6132603f167fe9c51c00361ee0c81d74a8f55d0ee2 | \
+        grep -v ee4fef0ef8be5053ebae4ce75acf062ddf3031fb | \
+        xargs -I{} git index-pack --rev-index -v {}
+        git status
+        git diff-index --quiet HEAD --