As a result of this commit

https://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=ba33775fd0302befddfc5102c51e0e9fb1f282d3

the value for lc_messages GUC in postgresql.conf is enclosed with
single quotes when the locale is other than C, else not as seen below:t

lc_messages = C # locale for system error message
lc_messages = 'en_US.UTF-8' # locale for system error message

The installer would read this GUC value and set it in the Locale
directive in /etc/postgres-reg.ini (on MacOS). Because of this
change the existing regex did not work and required change

tested on MacOS with both the locales i.e C and en_US.UTF-8

Testing done by: kritika.agarwal@enterprisedb.com

server/pgserver.xml.in

@@ -3444,7 +3444,7 @@
                 <setInstallerVariableFromRegEx>
                     <name>actuallocale</name>
                     <text>${serverconfig}</text>
-                    <pattern>^.*lc_messages\s*=\s*'([^']+)'\s+.*$</pattern>
+                    <pattern>^.*lc_messages\s*=\s*'?(([^ \t'])+)'?\s+.*$</pattern>
                     <substitution>\1</substitution>
                 </setInstallerVariableFromRegEx>