This patch makes the UUIDs in the XMP header optional, depending on the
setting of the environment variable GS_GENERATE_UUIDS.

If the environment variable GS_GENERATE_UUIDS is set to "0" or "no", it will
not write out the Document UUID field and also will write the Instance ID
field value as "".

Upstream does not want to do this.

See: https://bugs.ghostscript.com/show_bug.cgi?id=698208
diff -ur orig/gnu-ghostscript-9.14.0/devices/vector/gdevpdfe.c aa/gnu-ghostscript-9.14.0/devices/vector/gdevpdfe.c
--- orig/gnu-ghostscript-9.14.0/devices/vector/gdevpdfe.c	2017-07-09 23:30:28.960479189 +0200
+++ gnu-ghostscript-9.14.0/devices/vector/gdevpdfe.c	2017-07-10 01:04:12.252478276 +0200
@@ -617,7 +617,7 @@
         return code;
 
     /* PDF/A XMP reference recommends setting UUID to empty. If not empty must be a URI */
-    if (pdev->PDFA != 0)
+    if (pdev->PDFA != 0 || (getenv("GS_GENERATE_UUIDS") && (strcasecmp(getenv("GS_GENERATE_UUIDS"), "0") == 0 || strcasecmp(getenv("GS_GENERATE_UUIDS"), "no") == 0)))
         instance_uuid[0] = 0x00;
 
     cre_date_time_len = pdf_get_docinfo_item(pdev, "/CreationDate", cre_date_time, sizeof(cre_date_time));
@@ -719,15 +719,18 @@
             pdf_xml_tag_close(s, "rdf:Description");
             pdf_xml_newline(s);
 
-            pdf_xml_tag_open_beg(s, "rdf:Description");
-            pdf_xml_attribute_name(s, "rdf:about");
-            pdf_xml_attribute_value(s, instance_uuid);
-            pdf_xml_attribute_name(s, "xmlns:xapMM");
-            pdf_xml_attribute_value(s, "http://ns.adobe.com/xap/1.0/mm/");
-            pdf_xml_attribute_name(s, "xapMM:DocumentID");
-            pdf_xml_attribute_value(s, document_uuid);
-            pdf_xml_tag_end_empty(s);
-            pdf_xml_newline(s);
+            if (!getenv("GS_GENERATE_UUIDS") || (strcasecmp(getenv("GS_GENERATE_UUIDS"), "0") != 0 && strcasecmp(getenv("GS_GENERATE_UUIDS"), "no") != 0))
+            {
+                pdf_xml_tag_open_beg(s, "rdf:Description");
+                pdf_xml_attribute_name(s, "rdf:about");
+                pdf_xml_attribute_value(s, instance_uuid);
+                pdf_xml_attribute_name(s, "xmlns:xapMM");
+                pdf_xml_attribute_value(s, "http://ns.adobe.com/xap/1.0/mm/");
+                pdf_xml_attribute_name(s, "xapMM:DocumentID");
+                pdf_xml_attribute_value(s, document_uuid);
+                pdf_xml_tag_end_empty(s);
+                pdf_xml_newline(s);
+            }
 
             pdf_xml_tag_open_beg(s, "rdf:Description");
             pdf_xml_attribute_name(s, "rdf:about");
showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-04-14 22:48:52 +0200'>2020-04-14</span></td><td><a href='/guix/commit/gnu/packages/cook.scm?id=2e3d5fdf055906a7de356d8f161cebaa3a40e691'>gnu: cook: Fix test failure.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/cook.scm (cook)[arguments]: Override LC_ALL for one test.
</span></span></td><td>Marius Bakke</td></tr>
<tr><td><span title='2020-03-16 16:48:31 +0100'>2020-03-16</span></td><td><a href='/guix/commit/gnu/packages/cook.scm?id=1fddf8ef1702f96340d7bede8ecbd90b64c2019f'>gnu: cook: Fix.</a><span class='msg-avail'>...<span class='msg-tooltip'>This follows up on commit 5adc59e6fe8abb701df8fc97d56a6e60258318a4.

* gnu/packages/cook.scm (cook)[home-page]: Better.

Reported-by: Marius Bakke &lt;mbakke@fastmail.com&gt;
</span></span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2020-03-16 16:32:43 +0100'>2020-03-16</span></td><td><a href='/guix/commit/gnu/packages/cook.scm?id=5adc59e6fe8abb701df8fc97d56a6e60258318a4'>gnu: cook: Use archived home page.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/packages/cook.scm (cook)[home-page]: Use a Web Archived copy.
</span></span></td><td>Tobias Geerinckx-Rice</td></tr>