Fail faster on CI when Linux bootstrap fails

Raise an exception when dependencies fail to install. Also split the run
phase of the Linux bootstrap so that either of these failing commands
will cause the job to fail.

.github/workflows/main.yml

@@ -222,11 +222,10 @@ jobs:
       - uses: actions/checkout@v3
         with:
           fetch-depth: 2
-      - name: Bootstrap
+      - name: Bootstrap Python
-        run: |
+        run: python3 -m pip install --upgrade pip virtualenv
-          python3 -m pip install --upgrade pip virtualenv
+      - name: Bootstrap dependencies
-          sudo apt update
+        run: sudo apt update && python3 ./mach bootstrap
-          python3 ./mach bootstrap
       - name: Release build
         run: python3 ./mach build --release
       - name: Lockfile check

.github/workflows/pull-request.yml

@@ -15,11 +15,10 @@ jobs:
       - uses: actions/checkout@v3
         with:
           fetch-depth: 2
-      - name: Bootstrap
+      - name: Bootstrap Python
-        run: |
+        run: python3 -m pip install --upgrade pip virtualenv
-          python3 -m pip install --upgrade pip virtualenv
+      - name: Bootstrap dependencies
-          sudo apt update
+        run: sudo apt update && python3 ./mach bootstrap
-          python3 ./mach bootstrap
       - name: Release build
         run: python3 ./mach build --release
       - name: Unit tests

python/servo/bootstrap.py

@@ -59,11 +59,13 @@ def install_linux_deps(context, pkgs_ubuntu, pkgs_fedora, pkgs_void, force):
                 install = force = True
                 break
 
-    if install:
+    if not install:
-        print("Installing missing dependencies...")
+        return False
-        run_as_root(command + pkgs, force)
 
-    return install
+    print("Installing missing dependencies...")
+    if run_as_root(command + pkgs, force) != 0:
+        raise Exception("Installation of dependencies failed.")
+    return True
 
 
 def install_salt_dependencies(context, force):