ensure the pip in venv in install script

Close #1053

README.md

@@ -89,8 +89,8 @@ curl -sSL https://raw.githubusercontent.com/pdm-project/pdm/main/install-pdm.py
 (Invoke-WebRequest -Uri https://raw.githubusercontent.com/pdm-project/pdm/main/install-pdm.py -UseBasicParsing).Content | python -
 ```
 
-For security reasons, you should verify the checksum.
-The sha256 checksum is: `70ac95c53830ff41d700051c9caebd83b2b85b5d6066e8f853006f9f07293ff0`
+For security reasons, you should verify the checksum of `install-pdm.py`.
+The sha256 checksum is: `67dccb18923340e21f3d70f9c6a467d532c6a41b295d6f1ba884b27604074d38`
 
 The installer will install PDM into the user site and the location depends on the system:
 

README_zh.md

@@ -85,8 +85,8 @@ curl -sSL https://raw.githubusercontent.com/pdm-project/pdm/main/install-pdm.py
 (Invoke-WebRequest -Uri https://raw.githubusercontent.com/pdm-project/pdm/main/install-pdm.py -UseBasicParsing).Content | python -
 ```
 
-为安全起见，你应该检查文件的正确性。
-SHA256 校验和: `70ac95c53830ff41d700051c9caebd83b2b85b5d6066e8f853006f9f07293ff0`
+为安全起见，你应该检查 `install-pdm.py` 文件的正确性。
+SHA256 校验和: `67dccb18923340e21f3d70f9c6a467d532c6a41b295d6f1ba884b27604074d38`
 
 默认情况下，此脚本会将 PDM 安装在 Python 的用户目录下，具体位置取决于当前系统：
 

docs/docs/index.md

@@ -46,8 +46,8 @@ Like Pip, PDM provides an installation script that will install PDM into an isol
     (Invoke-WebRequest -Uri https://raw.githubusercontent.com/pdm-project/pdm/main/install-pdm.py -UseBasicParsing).Content | python -
     ```
 
-For security reasons, you should verify the checksum.
-The sha256 checksum is: `70ac95c53830ff41d700051c9caebd83b2b85b5d6066e8f853006f9f07293ff0`
+For security reasons, you should verify the checksum of `install-pdm.py`.
+The sha256 checksum is: `67dccb18923340e21f3d70f9c6a467d532c6a41b295d6f1ba884b27604074d38`
 
 The installer will install PDM into the user site and the location depends on the system:
 

install-pdm.py

@@ -285,6 +285,10 @@ class Installer:
 
         # Re-install the venv pip to ensure it's not DEBUNDLED
         # See issue/685
+        try:
+            _call_subprocess([str(venv_python), "-m", "ensurepip"])
+        except SystemExit:
+            pass
         _call_subprocess([str(venv_python), "-m", "pip", "install", "-IU", "pip"])
 
         if self.version:

news/1053.bugfix.md

+Ensure the pip module inside venv in installation script.