Support the PURPLE_PLUGIN_PATH environment variable.  This patch is based on
one from Nixpkgs, but properly handles the case where that variable is unset.

--- pidgin-2.10.11/libpurple/plugin.c.orig	2014-11-23 11:41:25.000000000 -0500
+++ pidgin-2.10.11/libpurple/plugin.c	2015-08-04 14:31:02.257366144 -0400
@@ -1178,8 +1178,19 @@
 void
 purple_plugins_init(void) {
 	void *handle = purple_plugins_get_handle();
+	const gchar *purple_plugin_path;
 
 	purple_plugins_add_search_path(LIBDIR);
+	purple_plugin_path = g_getenv("PURPLE_PLUGIN_PATH");
+	if (purple_plugin_path && *purple_plugin_path) {
+		gchar **paths = g_strsplit(purple_plugin_path, ":", -1);
+		if (paths) {
+			gchar **p;
+			for (p = paths; *p; ++p)
+				if (**p) purple_plugins_add_search_path(*p);
+		}
+		g_strfreev(paths);
+	}
 
 	purple_signal_register(handle, "plugin-load",
 						 purple_marshal_VOID__POINTER,
/></form></td></tr>
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<div class='path'>path: <a href='/guix/log/?id=79e074ea10875ff75ca613179c70de12d64b19f5'>root</a>/<a href='/guix/log/gnu?id=79e074ea10875ff75ca613179c70de12d64b19f5'>gnu</a>/<a href='/guix/log/gnu/services?id=79e074ea10875ff75ca613179c70de12d64b19f5'>services</a>/<a href='/guix/log/gnu/services/rsync.scm?id=79e074ea10875ff75ca613179c70de12d64b19f5'>rsync.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/services/rsync.scm?id=79e074ea10875ff75ca613179c70de12d64b19f5&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2019-03-04 15:22:58 +0100'>2019-03-04</span></td><td><a href='/guix/commit/gnu/services/rsync.scm?id=56a93cb975ddc33d50183fb122e2aafda026f18e'>services: Use 'file-append' for user account shells.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/services/cuirass.scm (cuirass-account): Use 'file-append' instead
of #~(string-append #$shadow "/sbin/nologin").
* gnu/services/monitoring.scm (zabbix-server-account): Likewise.
(zabbix-agent-account): Likewise.
* gnu/services/rsync.scm (rsync-account): Likewise.
* gnu/services/ssh.scm (%openssh-accounts): Likewise.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2017-09-23 21:07:27 +0100'>2017-09-23</span></td><td><a href='/guix/commit/gnu/services/rsync.scm?id=9db7e9be59820190a97de22ba72e71fa25f9d168'>gnu: Add rsync service.</a><span class='msg-avail'>...<span class='msg-tooltip'>* doc/guix.texi (Networking Services): Add rsync service documentation.
* gnu/services/rsync.scm (&lt;rsync-configuration&gt;): New file.
* gnu/tests/rsync.scm: New file.
* gnu/local.mk (GNU_SYSTEM_MODULES): Add new files.

Signed-off-by: Christopher Baines &lt;mail@cbaines.net&gt;
</span></span></td><td>Oleg Pykhalov</td></tr>