Auto merge of #25996 - humancalico:mach_pop, r=jdm

added pop!_os support for ./mach bootstrap

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Added ./mach bootstrap support for Pop!_OS

---
r? @jdm

<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `___` with appropriate data: -->
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #25965 (GitHub issue number if applicable)

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- [ ] There are tests for these changes OR
- [ ] These changes do not require tests because ___

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python/servo/bootstrap.py

@@ -361,6 +361,22 @@ def get_linux_distribution():
         else:
             raise Exception('unsupported version of %s: %s' % (distrib, version))
 
+        distrib, version = 'Ubuntu', base_version
+    elif distrib == 'Pop!_OS':
+        if '.' in version:
+            major, _ = version.split('.', 1)
+        else:
+            major = version
+
+        if major == '19':
+            base_version = '18.04'
+        elif major == '18':
+            base_version = '16.04'
+        elif major == '17':
+            base_version = '14.04'
+        else:
+            raise Exception('unsupported version of %s: %s' % (distrib, version))
+
         distrib, version = 'Ubuntu', base_version
     elif distrib.lower() == 'elementary':
         if version == '5.0':