Corrected version comparison to determine mc-health mode to use pre-1.7 (#3745)

Dockerfile

@@ -89,4 +89,8 @@ HEALTHCHECK --start-period=2m --retries=2 --interval=30s CMD mc-health
 ARG BUILDTIME=local
 ARG VERSION=local
 ARG REVISION=local
-RUN echo "buildtime=${BUILDTIME}\nversion=${VERSION}\nrevision=${REVISION}" > /etc/image.properties
+COPY <<EOF /etc/image.properties
+buildtime=${BUILDTIME}
+version=${VERSION}
+revision=${REVISION}
+EOF

scripts/start-utils

@@ -261,22 +261,23 @@ function compare_version() {
   fi
 
   # Handle version channels ('a', 'b', or numeric)
-  if [[ $left_version == a* || $left_version == b* ]]; then
+  if [[ $left_version == a* ]]; then
     left_version=${left_version:1}
+    left_version_channel=1
+  elif [[ $left_version == b* ]]; then
+    left_version=${left_version:1}
+    left_version_channel=2
+  else 
+    left_version_channel=3    
   fi
-
-  if [[ $right_version == a* || $right_version == b* ]]; then
+  if [[ $right_version == a* ]]; then
     right_version=${right_version:1}
-  fi
-
-  local left_version_channel=${left_version:0:1}
-  if [[ $left_version_channel =~ [0-9] ]]; then
-    left_version_channel='r'
-  fi
-
-  local right_version_channel=${right_version:0:1}
-  if [[ $right_version_channel =~ [0-9] ]]; then
-    right_version_channel='r'
+    right_version_channel=1
+  elif [[ $right_version == b* ]]; then
+    right_version=${right_version:1}
+    right_version_channel=2
+  else 
+    right_version_channel=3    
   fi
 
   if [[ $comparison == "lt" && $left_version_channel < $right_version_channel ]]; then