ScriptInfo: do not mix datestamp into the version

At the time I wrote that code, I was mainly concerned with ensuring that
generated version strings do not clash. However, there are compelling
reasons to avoid "false negatives" as well (two scripts which are
actually the same, but end up with differing version strings).

When mixing in the datestamp with the hash, a false negative will happen
if the script's last modified date is not preserved when copied between
systems. This makes data provenance more difficult, because two systems
may have identical installations content-wise, but different version
strings due to timestamp skew.

So, let's keep it simpler: use the content hash if available (i.e.:
if the script contents can be read), and the datestamp only if not.

Author: ctrueden

src/main/java/org/scijava/script/ScriptInfo.java

@@ -322,16 +322,15 @@ public String getLocation() {
 	public String getVersion() {
 		final File file = new File(path);
 		if (!file.exists()) return null; // no version for non-existent script
-		final Date lastModified = FileUtils.getModifiedTime(file);
-		final String datestamp =
-			new SimpleDateFormat("yyyy-MM-dd-HH:mm:ss").format(lastModified);
 		try {
-			final String hash = DigestUtils.bestHex(FileUtils.readFile(file));
-			return datestamp + "-" + hash;
+			return DigestUtils.bestHex(FileUtils.readFile(file));
 		}
 		catch (final IOException exc) {
 			log.error(exc);
 		}
+		final Date lastModified = FileUtils.getModifiedTime(file);
+		final String datestamp =
+			new SimpleDateFormat("yyyy-MM-dd-HH:mm:ss").format(lastModified);
 		return datestamp;
 	}