Remove non-standard : anchors

ci/affects-files.sh

@@ -3,23 +3,26 @@
 # Checks if a CI build affects one or more path patterns.  Each command-line
 # argument is checked in series.
 #
-# Bash regular expresses are permitted in the pattern, and the colon (':')
-# character is guaranteed to appear before and after each affected file (and thus
-# can be used as an anchor), eg:
-#     .rs:    -- any file or directory ending in .rs
-#     .rs     -- also matches foo.rs.bar
-#     :snap/  -- anything under the snap/ subdirectory
-#     snap/   -- also matches foo/snap/
+# Bash regular expressions are permitted in the pattern:
+#     ./affects-files.sh .rs$    -- any file or directory ending in .rs
+#     ./affects-files.sh .rs     -- also matches foo.rs.bar
+#     ./affects-files.sh ^snap/  -- anything under the snap/ subdirectory
+#     ./affects-files.sh snap/   -- also matches foo/snap/
 #
+set -e
+cd "$(dirname "$0")"/..
 
 if ci/is-pr.sh; then
   affectedFiles="$(buildkite-agent meta-data get affected_files)"
   echo "Affected files in this PR: $affectedFiles"
 
+  IFS=':' read -ra files <<< "$affectedFiles"
   for pattern in "$@"; do
-    if [[ ":$affectedFiles:" =~ $pattern ]]; then
-      exit 0
-    fi
+    for file in "${files[@]}"; do
+      if [[ $file =~ $pattern ]]; then
+        exit 0
+      fi
+    done
   done
 
   exit 1