[GNC] Gnucash 3.3 crash after upgrading from Ubuntu 18.04 to 18.10

[Colin Law]

Just upgraded my Ubuntu 18.04 to 18.10.  This upgraded GC from 2.6.19 (at
least I think it was 19) to 3.3 and now GC crashes immediately on startup.
Starting in a terminal gives result below.  There is nothing in the trace
file.  On another machine with a fresh install of 18.10 GC 3.3 runs fine so
I guess it is to with updated file locations or something.

Colin

$ gnucash
Backtrace:
In ice-9/boot-9.scm:
  2994:20 19 (_)
   2312:4 18 (save-module-excursion _)
  3014:26 17 (_)
In unknown file:
          16 (primitive-load-path "gnucash/utilities" #<procedure 55…>)
In utilities.scm:
     28:0 15 (_)
In ice-9/boot-9.scm:
  3377:20 14 (process-use-modules _)
   222:17 13 (map1 (((gnucash core-utils))))
  3378:31 12 (_ ((gnucash core-utils)))
  2800:17 11 (resolve-interface (gnucash core-utils) #:select _ # _ # …)
In ice-9/threads.scm:
    390:8 10 (_ _)
In ice-9/boot-9.scm:
  2726:13  9 (_)
In ice-9/threads.scm:
    390:8  8 (_ _)
In ice-9/boot-9.scm:
  2994:20  7 (_)
   2312:4  6 (save-module-excursion _)
  3014:26  5 (_)
In unknown file:
           4 (primitive-load-path "gnucash/core-utils" #<procedure 5…>)
In core-utils.scm:
     40:0  3 (_)
In ice-9/boot-9.scm:
  2071:24  2 (call-with-deferred-observers #<procedure 7f649fe8c2b8 …>)
   260:13  1 (for-each #<procedure 55f6e50dd4e0 at ice-9/boot-9.scm…> …)
In unknown file:
           0 (scm-error misc-error #f "~A ~S" ("Undefined variab…" …) …)

ERROR: In procedure scm-error:
Undefined variable: gnc-build-userdata-path