pack.sh: versioning adjustments

* When building on AppVeyor:

    Drop prerelease-suffix on tagged commits (official releases),
    or set canary-suffix when building the master-branch,
    or set rc-suffix when building a release-branch.

* When building from Git repo:

    Get commit SHA from local git-repo.
    Always set dev-suffix.

* Otherwise:

    Always set dev-suffix.

Following up a little bit on fuse-open#208, I think this new logic is less awkward.

I also added a canary-suffix on master-builds, and the idea is to set up a
canary-channel on NPM where we can easily publish the latest master-build.

scripts/pack.sh

@@ -10,32 +10,28 @@ rm -rf ${DST:?}/* 2> /dev/null || :
 mkdir -p $DST
 
 # Detect version info
-COMMIT=`git rev-parse HEAD 2> /dev/null || :`
 VERSION=`cat package.json | grep version | head -1 | awk -F: '{ print $2 }' | sed 's/[\",]//g' | tr -d '[[:space:]]'`
+BUILD_NUMBER="0"
+SUFFIX="dev"
+COMMIT="N/A"
 
-if [ -n "$APPVEYOR_REPO_BRANCH" ]; then
-    BRANCH=$APPVEYOR_REPO_BRANCH
-elif [ -n "$COMMIT" ]; then
-    BRANCH=`git rev-parse --abbrev-ref HEAD`
-else
-    BRANCH="unknown"
-    COMMIT="unknown"
-fi
-
-if [ -n "$APPVEYOR_BUILD_NUMBER" ]; then
+if [ -n "$APPVEYOR" ]; then
     BUILD_NUMBER=$APPVEYOR_BUILD_NUMBER
-else
-    BUILD_NUMBER=0
-fi
-
-# Use {dev, master}-COMMIT as prerelease suffix on non-release branches
-if [ -n "$APPVEYOR_REPO_TAG_NAME" ]; then
-    # Don't set prerelease suffix on AppVeyor builds started by tag
-    SUFFIX=
-elif [ "$BRANCH" = master ]; then
-    SUFFIX="master-${COMMIT:0:7}"
-elif [[ "$BRANCH" != release-* ]]; then
-    SUFFIX="dev-${COMMIT:0:7}"
+    COMMIT=$APPVEYOR_REPO_COMMIT
+
+    # Drop prerelease-suffix on tagged commits (official releases),
+    # or set canary-suffix when building the master-branch,
+    # or set rc-suffix when building a release-branch.
+    if [ -n "$APPVEYOR_REPO_TAG_NAME" ]; then
+        SUFFIX=""
+    elif [ "$APPVEYOR_REPO_BRANCH" = master ]; then
+        SUFFIX="canary"
+    elif [ "$APPVEYOR_REPO_BRANCH" = release-* ]; then
+        SUFFIX="rc"
+    fi
+elif [ -d .git ]; then
+    # Get commit SHA from local git-repo.
+    COMMIT=`git rev-parse HEAD 2> /dev/null || :`
 fi
 
 if [ -n "$SUFFIX" ]; then