use branch names in format compatibility test

Summary:
We had to go back and update the g++ path for 4.4.fb-4.8.fb. So the
path is now fixed on the branches, but can't be fixed on the tags since they're
immutable. By making format compatibility tests use branch names (when
available), backported fixes like this will be used without having to re-release.

Also removed v1.5.7 and v2.1 because make fails.

Test Plan:
  $ build_tools/rocksdb-lego-determinator run_format_compatible

Reviewers: sdong, lightmark, IslamAbdelRahman

Reviewed By: IslamAbdelRahman

Subscribers: andrewkr, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D59355

tools/check_format_compatible.sh

@@ -4,7 +4,7 @@
 # ./ldb needs to be avaible to be executed.
 #
 # Usage: <SCRIPT> [checkout]
-# `checkout` can be a tag, commit or branch name. Will build using it and check DBs generated by all previous tags can be opened by it.
+# `checkout` can be a tag, commit or branch name. Will build using it and check DBs generated by all previous branches (or tags for very old versions without branch) can be opened by it.
 # Return value 0 means all regression tests pass. 1 if not pass.
 
 scriptpath=`dirname $BASH_SOURCE`
@@ -41,10 +41,8 @@ with open('${input_data[$i]}', 'w') as f:
 EOF
 done
 
-# v2.1 or older doesn't pass the debug build but OK with release build
-declare -a need_release_tags=("v1.5.7" "v2.1")
-declare -a tags=("v2.5" "v2.4" "v2.3" "v2.2" "v2.8" "v3.0" "v3.1" "v3.2" "v3.3" "v3.4" "rocksdb-3.5.1" "rocksdb-3.6.2" "rocksdb-3.7" "rocksdb-3.8" "rocksdb-3.9" "v3.10" "v3.11" "v3.12.1" "v3.13.1" "v4.0" "v4.1" "v4.2" "v4.3" "v4.3.1" "v4.4")
-declare -a forward_compatible_tags=("v3.10" "v3.11" "v3.12.1" "v3.13.1" "v4.0" "v4.1" "v4.2" "v4.3.1" "v4.4")
+declare -a checkout_objs=("v2.2" "v2.3" "v2.4" "v2.5" "2.8.fb" "3.0.fb" "3.1.fb" "3.2.fb" "3.3.fb" "3.4.fb" "3.5.fb" "3.6.fb" "3.7.fb" "3.8.fb" "3.9.fb" "3.10.fb" "3.11.fb" "3.12.fb" "3.13.fb" "4.0.fb" "4.1.fb" "4.2.fb" "4.3.fb" "4.4.fb" "4.5.fb" "4.6.fb" "4.7.fb" "4.8.fb")
+declare -a forward_compatible_checkout_objs=("3.10.fb" "3.11.fb" "3.12.fb" "3.13.fb" "4.0.fb" "4.1.fb" "4.2.fb" "4.3.fb" "4.4.fb")
 
 generate_db()
 {
@@ -69,13 +67,13 @@ compare_db()
 }
 
 set -e
-for tag in "${tags[@]}" "${need_release_tags[@]}"
+for checkout_obj in "${checkout_objs[@]}"
 do
-   echo == Generating DB from "$tag" ...
-   git checkout $tag
+   echo == Generating DB from "$checkout_obj" ...
+   git checkout $checkout_obj
    make clean
    make ldb -j32
-   generate_db $input_data_path $test_dir/$tag
+   generate_db $input_data_path $test_dir/$checkout_obj
 done
 
 checkout_flag=${1:-"master"}
@@ -88,28 +86,19 @@ compare_base_db_dir=$test_dir"/base_db_dir"
 echo == Generate compare base DB to $compare_base_db_dir
 generate_db $input_data_path $compare_base_db_dir
 
-for tag in "${tags[@]}"
+for checkout_obj in "${checkout_objs[@]}"
 do
-   echo == Opening DB from "$tag" using debug build of $checkout_flag ...
-   compare_db $test_dir/$tag $compare_base_db_dir db_dump.txt
+   echo == Opening DB from "$checkout_obj" using debug build of $checkout_flag ...
+   compare_db $test_dir/$checkout_obj $compare_base_db_dir db_dump.txt
 done
 
-echo == Building $checkout_flag release
-git checkout $checkout_flag
-make release
-for tag in "${need_release_tags[@]}"
+for checkout_obj in "${forward_compatible_checkout_objs[@]}"
 do
-   echo == Opening DB generated by "$tag" using release build of $checkout_flag ...
-   compare_db $test_dir/$tag $compare_base_db_dir db_dump.txt
-done
-
-for tag in "${forward_compatible_tags[@]}"
-do
-   echo == Build "$tag" and try to open DB generated using $checkout_flag...
-   git checkout $tag
+   echo == Build "$checkout_obj" and try to open DB generated using $checkout_flag...
+   git checkout $checkout_obj
    make clean
    make ldb -j32
-   compare_db $test_dir/$tag $compare_base_db_dir forward_${tag}_dump.txt
+   compare_db $test_dir/$checkout_obj $compare_base_db_dir forward_${checkout_obj}_dump.txt
 done
 
 echo ==== Compatibility Test PASSED ====