fix yum proxy regex (closes #47797) (#47800)

* Modify yum/tasks/proxy.yml to usernames that expose regex bug

* Fix bad regex backref/interpolation w/yum proxy username

A yum proxy username that begins with a number was being
interpolated as part of the backref, resulting in an error:
"sre_constants.error: invalid group reference"

Closes #47797

lib/ansible/modules/packaging/os/yum.py

@@ -710,7 +710,7 @@ class YumModule(YumDnf):
                     for item in scheme:
                         os.environ[item + "_proxy"] = re.sub(
                             r"(http://)",
-                            r"\1" + namepass, proxy_url
+                            r"\g<1>" + namepass, proxy_url
                         )
             yield
         except yum.Errors.YumBaseError:

test/integration/targets/yum/tasks/proxy.yml

@@ -6,7 +6,7 @@
 
     - lineinfile:
         path: /etc/tinyproxy/tinyproxy.conf
-        line: "BasicAuth testuser testpassword"
+        line: "BasicAuth 1testuser 1testpassword"
         state: present
 
     # systemd doesn't play nice with this in a container for some reason
@@ -15,7 +15,7 @@
 
     - lineinfile:
         path: /etc/yum.conf
-        line: "proxy=http://testuser:testpassword@127.0.0.1:8888"
+        line: "proxy=http://1testuser:1testpassword@127.0.0.1:8888"
         state: present
 
     - yum:
@@ -35,7 +35,7 @@
 
     - lineinfile:
         path: /etc/yum.conf
-        line: "proxy=http://testuser:testpassword@127.0.0.1:8888"
+        line: "proxy=http://1testuser:1testpassword@127.0.0.1:8888"
         state: absent
 
     - lineinfile:
@@ -45,12 +45,12 @@
 
     - lineinfile:
         path: /etc/yum.conf
-        line: "proxy_username=testuser"
+        line: "proxy_username=1testuser"
         state: present
 
     - lineinfile:
         path: /etc/yum.conf
-        line: "proxy_password=testpassword"
+        line: "proxy_password=1testpassword"
         state: present
 
     - yum:
@@ -75,7 +75,7 @@
 
     - lineinfile:
         path: /etc/yum.conf
-        line: "proxy=http://testuser:testpassword@127.0.0.1:8888"
+        line: "proxy=http://1testuser:1testpassword@127.0.0.1:8888"
         state: absent
 
     - lineinfile:
@@ -85,12 +85,12 @@
 
     - lineinfile:
         path: /etc/yum.conf
-        line: "proxy_username=testuser"
+        line: "proxy_username=1testuser"
         state: absent
 
     - lineinfile:
         path: /etc/yum.conf
-        line: "proxy_password=testpassword"
+        line: "proxy_password=1testpassword"
         state: absent
   when:
     - (ansible_distribution in ['RedHat', 'CentOS', 'ScientificLinux'] and ansible_distribution_major_version|int == 7)