install_packages: add basic 5-time retry for Other Apt Update

api

@@ -518,19 +518,6 @@ Package: $package_name" > ~/$package_name/DEBIAN/control
     echo "$package_name is already installed and no changes would be made. Skipping..."
   else
 
-    #Before apt update, check if local repo still exists
-    if [ "$using_local_packages" == 1 ] && [ ! -f /tmp/pi-apps-local-packages/Packages ];then
-      error "User error: Uh-oh, the /tmp/pi-apps-local-packages folder went missing while installing packages.\nThis usually happens if you try to install several apps at the same time in multiple terminals."
-    fi
-
-    #run an apt update
-    apt_update "${apt_flags[@]}" || exit 1
-
-    #After apt update, check again if local repo still exists
-    if [ "$using_local_packages" == 1 ] && [ ! -f /tmp/pi-apps-local-packages/Packages ];then
-      error "User error: Uh-oh, the /tmp/pi-apps-local-packages folder went missing while installing packages.\nThis usually happens if you try to install several apps at the same time in multiple terminals."
-    fi
-
     #Build .deb file for the dummy package
     local output="$(dpkg-deb --build ~/$package_name 2>&1)"
     if [ $? != 0 ] || [ ! -f ~/$package_name.deb ];then
@@ -539,12 +526,32 @@ Package: $package_name" > ~/$package_name/DEBIAN/control
       error "install_packages(): failed to create dummy deb ${package_name}!"
     fi
 
-    #install dummy deb
-    status "Installing the $package_name package..."
+    #Before apt update, check if local repo still exists
+    if [ "$using_local_packages" == 1 ] && [ ! -f /tmp/pi-apps-local-packages/Packages ];then
+      error "User error: Uh-oh, the /tmp/pi-apps-local-packages folder went missing while installing packages.\nThis usually happens if you try to install several apps at the same time in multiple terminals."
+    fi
 
-    apt_lock_wait
-    local output="$(sudo -E apt install -fy --no-install-recommends --allow-downgrades "${apt_flags[@]}" ~/$package_name.deb 2>&1 | less_apt | tee /dev/stderr)"
-    status "Apt finished."
+    local i=0
+    while [ $i -le 5 ];do #retry loop ; run apt update and apt install again if apt's records of the local repo goes missing
+      #run an apt update
+      apt_update "${apt_flags[@]}" || exit 1
+
+      #install dummy deb
+      status "Installing the $package_name package..."
+
+      apt_lock_wait
+      local output="$(sudo -E apt install -fy --no-install-recommends --allow-downgrades "${apt_flags[@]}" ~/$package_name.deb 2>&1 | less_apt | tee /dev/stderr)"
+      status "Apt finished."
+
+      if [ "$using_local_packages" == 1 ] && [ ! -f /var/lib/apt/lists/_tmp_pi-apps-local-packages_._Packages ];then
+        #another apt update process deleted apt's knowledge of the pi-apps local repo. Warn the user and try again, up to 5 tries.
+        i=$((i+1))
+        warning "Local packages failed to install because another apt update process erased apt's knowledge of the pi-apps local repository.\nTrying again... (attempt $i of 5)"
+      else
+        #apt may have succeeded or failed, but exit retry loop for Other Apt Update
+        break
+      fi
+    done
 
     errors="$(echo "$output" | grep '^[(E)|(Err]:')"
     if [ ! -z "$errors" ];then