Turn top-level Cargo.toml into a virtual manifest

ci/crate-version.sh

@@ -1,17 +1,26 @@
 #!/usr/bin/env bash
 #
-# Outputs the current crate version
+# Outputs the current crate version from a given Cargo.toml
 #
 set -e
 
-cd "$(dirname "$0")"/..
+Cargo_toml=$1
+[[ -n $Cargo_toml ]] || {
+  echo "Usage: $0 path/to/Cargo.toml"
+  exit 0
+}
+
+[[ -r $Cargo_toml ]] || {
+  echo "Error: unable to read $Cargo_toml"
+  exit 1
+}
 
 while read -r name equals value _; do
   if [[ $name = version && $equals = = ]]; then
     echo "${value//\"/}"
     exit 0
   fi
-done < <(cat Cargo.toml)
+done < <(cat "$Cargo_toml")
 
 echo Unable to locate version in Cargo.toml 1>&2
 exit 1