hashcache now permits partial hash matches (common practice in git)

hashcache

@@ -39,8 +39,16 @@ _retrieve()
   hash="$1"
 
   # if multiple identical hashes exist, then the last one takes precedence
-  # (ideally, such a thing should never happen, but it's best to be prepared)
+  # (ideally, such a thing should never happen, but it's best to be prepared);
-  grep "^$hash " "$cachefile" \
+  # note that we *do not* check for a space after the hash, which allows for
+  # partial hashes to be matched (common practice for Git due to its long
+  # hashes); this may cause problems with other version control systems---such
+  # as SVN---that use revision numbers, in which case this implementation will
+  # have to be changed to accept a flag for whether or not to accept partial
+  # matches, or it must operate under the assumption that the commits are always
+  # processed in reverse order and (as such) the tail in this pipeline will
+  # always return the intended result
+  grep "^$hash" "$cachefile" \
     | tail -n1 \
     | cut -d' ' -f2-
 }