Bug 797743 - Monetary amounts are occasionally rendered in fractions

If monetary is already in decimal, don't convert. If monetary is
exact (x/y) then convert to its SCU.

As a result, monetary amounts in an arbitrary precision will be
displayed unchanged, e.g. US$0.1442, whereas exact monetary amounts
will be displayed using the currency's SCU e.g. US$1/3 -> $0.33

gnucash/report/report-system/html-style-info.scm

@@ -267,9 +267,13 @@
   (xaccPrintAmount datum (gnc-default-print-info #f)))
 
 (define (gnc:default-html-gnc-monetary-renderer datum params)
-  (xaccPrintAmount                                                 
-   (gnc:gnc-monetary-amount datum)                                    
-   (gnc-commodity-print-info (gnc:gnc-monetary-commodity datum) #t)))
+  (let* ((comm (gnc:gnc-monetary-commodity datum))
+         (scu (gnc-commodity-get-fraction comm))
+         (amount (gnc:gnc-monetary-amount datum))
+         (amt-display (if (exact? amount)
+                          (gnc-numeric-convert amount scu GNC-HOW-RND-ROUND)
+                          amount)))
+    (xaccPrintAmount amt-display (gnc-commodity-print-info comm #t))))
 
 (define (gnc:default-html-number-renderer datum params)  
   (xaccPrintAmount

gnucash/report/standard-reports/test/test-portfolios.scm

@@ -91,7 +91,7 @@
       (set-option! options "General" "Price Source" 'weighted-average)
       (let ((sxml (options->sxml portfolio-uuid options "'weighted-average")))
         (test-equal "portfolio: weighted-average"
-          '("AAPL" "AAPL" "NASDAQ" "1.00" "$233.33" "$233 + 1/3")
+          '("AAPL" "AAPL" "NASDAQ" "1.00" "$233.33" "$233.33")
           (sxml->table-row-col sxml 1 1 #f))))
     (teardown)))