release.sh: use git describe --abbrev=10

Without --abbrev flag it may produce different number of hash characters
on different instances. It depends on the state of Git repo itself.

Author: starius

docs/release.md

@@ -23,13 +23,13 @@ make docker-release tag=v0.31.3-beta
 This will create the release artifacts in the `loop-v0.31.3-beta` directory.
 
 If you want to build from an untagged commit, first check it out, then use the
-output of `git describe` as the tag:
+output of `git describe --abbrev=10` as the tag:
 
 ```bash
-git describe
-# v0.31.2-beta-128-gfa80357
+git describe --abbrev=10
+# v0.31.2-beta-135-g35d0fa26ac
 
-make docker-release tag=v0.31.2-beta-128-gfa80357
+make docker-release tag=v0.31.2-beta-135-g35d0fa26ac
 ```
 
 You can filter the target platforms to speed up the build process. For example,

release.sh

@@ -41,7 +41,7 @@ check_tag() {
     TAG=$1
 
     # If a tag is specified, ensure that tag is present and checked out.
-    if [[ $TAG != $(git describe) ]]; then
+    if [[ $TAG != $(git describe --abbrev=10) ]]; then
         red "tag $TAG not checked out"
         exit 1
     fi
@@ -50,7 +50,7 @@ check_tag() {
     # output of "git describe" for an untagged commit, skip verification.
     # The pattern is: <tag_name>-<number_of_commits>-g<abbreviated_commit_hash>
     # Example: "v0.31.2-beta-122-g8c6b73c".
-    if [[ $TAG =~ -[0-9]+-g([0-9a-f]+)$ ]]; then
+    if [[ $TAG =~ -[0-9]+-g([0-9a-f]{10})$ ]]; then
         # This looks like a "git describe" output. Make sure the hash
         # described is a prefix of the current commit.
         DESCRIBED_HASH=${BASH_REMATCH[1]}