Introduce lock and fix error emission

.drone.yml

@@ -74,7 +74,19 @@ steps:
   pull: if-not-exists
   image: leophys/pikaur:0.2
   commands:
-  - /usr/bin/pikaur -Sy --noconfirm electron-ozone|tee /output/electron-ozone.log
+  - |
+    if [ -f /output/lock ]; then
+      while [ -f /output/lock ]; do
+        sleep 10
+        echo "Waiting $(cat /output/lock)"
+      done
+    else
+      echo "electron-ozone" >> /output/lock
+    fi
+  - |
+    set -euo pipefail
+    /usr/bin/pikaur -Sy --noconfirm electron-ozone|tee /output/electron-ozone.log
+  - rm -f /output/lock
   volumes:
   - name: build_electron-ozone
     path: /build
@@ -142,6 +154,10 @@ steps:
     M_SUB: "[electron-ozone] FAILURE"
   commands:
   - /sendmail.sh /output/electron-ozone.log
+  - rm -f /output/lock
+  volumes:
+  - name: output
+    path: /output
 
 volumes:
 - name: output
@@ -232,7 +248,19 @@ steps:
   pull: if-not-exists
   image: leophys/pikaur:0.2
   commands:
-  - /usr/bin/pikaur -Sy --noconfirm discord_arch_electron|tee /output/discord_arch_electron.log
+  - |
+    if [ -f /output/lock ]; then
+      while [ -f /output/lock ]; do
+        sleep 10
+        echo "Waiting $(cat /output/lock)"
+      done
+    else
+      echo "discord_arch_electron" >> /output/lock
+    fi
+  - |
+    set -euo pipefail
+    /usr/bin/pikaur -Sy --noconfirm discord_arch_electron|tee /output/discord_arch_electron.log
+  - rm -f /output/lock
   volumes:
   - name: build_discord_arch_electron
     path: /build
@@ -300,6 +328,10 @@ steps:
     M_SUB: "[discord_arch_electron] FAILURE"
   commands:
   - /sendmail.sh /output/discord_arch_electron.log
+  - rm -f /output/lock
+  volumes:
+  - name: output
+    path: /output
 
 volumes:
 - name: output