0602c5bd626181f95ddf0999af7bbb25201cf9f2
max
  Thu Apr 3 02:13:44 2014 -0700
oops forgot to check for null pointer in last commit.
diff --git src/hg/lib/hdb.c src/hg/lib/hdb.c
index d56e3aa..c8703c9 100644
--- src/hg/lib/hdb.c
+++ src/hg/lib/hdb.c
@@ -1285,30 +1285,32 @@
 path = replaceChars(fileName, "/gbdb/", newGbdbLoc);
 return path;
 }
 
 char *hReplaceGbdb(char* fileName)
  /* Returns a gbdb filename, potentially rewriting it according to hg.conf
   * If the settings gbdbLoc1 and gbdbLoc2 are found, try them in order, by 
   * replacing /gbdb/ with the new locations.
   * If after the replacement of gbdbLoc1 the resulting fileName does not exist,
   * gbdbLoc2 is used.
   * This function does not guarantee that the returned filename exists.
   * We assume /gbdb/ does not appear somewhere inside a fileName.
   * Result has to be free'd.
  * */
 {
+if (fileName == NULL)
+    return fileName;
 char *path = hReplaceGbdbLocal(fileName);
 if (fileExists(path))
     return path;
 
 // if the file did not exist, replace with gbdbLoc2
 char* newGbdbLoc = cfgOption("gbdbLoc2");
 if (newGbdbLoc==NULL)
     return path;
 
 freeMem(path);
 path = replaceChars(fileName, "/gbdb/", newGbdbLoc);
 return path;
 }
 
 char *hReplaceGbdbSeqDir(char *path, char *db)